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Sum= 31,006
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302111999Traffic & SafetyTraffic SafetyIdentification of Severe Crash Factors and Countermeasures in North Carolina
<P><FONT face=Verdana size=2>The eight Southeastern States in FHWA's Region IV have been ranked among the highest nationally in terms of fatal crash rates in recent years. These eight states include North Carolina, Alabama, Florida, Georgia, Kentucky, Mississippi, Tennessee, and South Carolina. These eight states accounted for approximately 25 percent of the nation's total fatalities in 1995 and a fatality rate about 20 percent above the national mean.<BR><BR>I</FONT><FONT face=Verdana size=2>n 1995, North Carolina ranked 9th of the 50 states in terms of total highway-related deaths, with 1,418 people killed. The fatality rate of 1.9 (people killed per 100 million vehicle miles of travel) ranked North Carolina 20th nationally. In response to these trends in traffic fatalities, the North Carolina DOT and other state DOT's in Region IV have expressed an interest in further studying fatal crash causes and possible countermeasures.<BR><BR></FONT><FONT face=Verdana size=2>The main objective of this study is to identify factors associated with fatal and serious injury crashes in North Carolina and recommend appropriate countermeasures to reduce their frequency.<BR><BR></FONT><FONT face=Verdana size=2>This report examines the roadway, crash, vehicle, individual, and environmental factors that are associated with fatal and serious injury crashes in North Carolina between 1993 and 1997. The initial analysis identifies road classifications, geographic characteristics, and time trends related to severe crashes using Highway Safety Information systems (HSIS) segment and crash data. HSIS system highways in North Carolina include the state primary and major secondary routes. Non-HSIS roads include local streets and minor secondary streets. Both HSIS and non HSIS data are used in the more detailed section of the study to analyze the severe crash factors on all HSIS highways, two-lane urban HSIS highways, two lane rural HSIS, urban non-HSIS routes, and rural non-HSIS routes.<BR><BR></FONT><FONT face=Verdana size=2>In this report, a test of the standard error of a binomial proportion is used to find the statistical significance of the roadway, crash, vehicle, individual, and environmental factors related to severe crashes. The initial analysis shows that urban and rural two-lane roads are associated with the highest crash severity, mountain counties have the highest proportion of severe crashes, and crash severity remained stable for some of the most severe crash types. Factors associated with significantly high crash severity on all roadway types include curve, run off road, utility pole, tree, head-on, pedestrian, bicycle, darkness, and alcohol use. The final section of the report recommends countermeasures that can be used to reduce the incidence of fatal and serious injury crashes associated with these factors.</FONT></P>
<P><FONT face=Verdana size=2>This report summarizes the factors associated with serious and fatal injury crashes in North Carolina and suggests possible countermeasures to combat these contributing factors. To achieve the greatest severe crash reduction, a systematic approach for identifying combinations of severe crash factors should be followed. First, specific sites with a high number of severe crashes should be identified. Then, the significant contributing factors at those sites should be identified and treated with appropriate countermeasures.<BR><BR></FONT><FONT face=Verdana size=2>Significant severe crash factors identified earlier in the report include curve, run-off-road, utility pole, tree, head-on, pedestrian, bicycle, darkness, and alcohol crashes. The countermeasures recommended in Part III can be used separately or in combination to reduce the number and severity of crashes that occur as a result of these factors. Ultimately, reductions in these types of crashes will result in fewer severe injuries and fatalities on North Carolina roadways.</FONT></P>
Mustan KadibhaiMay 1999 - August 2001
102
Complete
1
2001-003
2
  
303192001Traffic & SafetyTraffic SafetySoutheast Regional Fatal Study - A Causual Chain Analysis in North Carolina
<FONT size=2><FONT face=Verdana size=2><BR><BR><br><P>In 1995, North Carolina ranked 9th of the 50 states in terms of total highway-related deaths. During that year, 1,418 people died on the State's highways. In response to these trends in traffic deaths, the State DOTs of Region IV and the FHWA wanted to better understand and prevent fatal crashes and their causal factors. The Causal Chain Analysis provided herein reviewed the chain of events of 150 fatal crashes. Then, each fatal crash was studied to see what effect select safety treatments would have had on the outcome of the crash. Causal chain analysis aims to determine if the treatment would have "broken the chain." By breaking the "chain" then the fatal crash would have been either prevented altogether or at least have been limited in severity.<BR><BR>The main objectives of this study are:</P><br><UL><br><LI>To complete the North Carolina portion of the casual chain analysis for the regional; pooled fund study for a sample of fatal crashes [Georgia Institute of Technology, Pooled fund study no. SPR-3 (057) "Investigation and Identification of Principal Factors Contributing to Fatal Crashes in the Southeastern United States"].</FONT><FONT size=2><FONT face="Times New Roman"> </FONT></FONT><FONT face=Verdana size=2><BR></LI><br><LI>To develop a ranked comprehensive list of candidate countermeasures likely to be effective for reducing both the number and severity of fatal crashes on two-lane rural roads in North Carolina. This list will include countermeasures ranked according to their expected influence on fatal crash frequency and severity for two-lane rural roads. The list will be based upon the findings of casual analyses of actual fatal crashes.</LI></UL></FONT><FONT size=2></FONT></FONT>
<P><FONT face=Verdana size=2>The application of the findings of this study may be tempered because the crashes were a subset of all reported crashes. These crashes included 150 randomly selected rural two-lane fatal crashes reported in North Carolina in 1997.<BR><BR></FONT><FONT face=Verdana size=2>The recommended next step would be to find areas where the countermeasures may be applied. One such method would be to develop warranting criteria in the Highway Safety Improvement Program (HSIP) to identify locations where these countermeasures may be applied. However, it is recommended to expand the data to multiple years and to all reported crashes. This <STRONG><A href="http://www.ncdot.org/doh/preconstruct/tpb/research/download/2001-19table_abstract.doc">table</A></STRONG>; shows the countermeasures reviewed which are sorted by the crash modification factor, where the crash modification factor exceeded five percent.&nbsp; <A href="http://www.ncdot.org/doh/preconstruct/tpb/research/download/2001-19table_abstract.doc">(Click here to view the table.)</A><BR><BR></FONT><FONT face=Verdana size=2>This list includes countermeasures ranked according to their expected influence on fatal crash frequency and severity for two-lane rural roads.<BR><BR></FONT><FONT face=Verdana size=2>Another opportunity to apply the results of this project is in the driveway permit process and requirements. Since the traversable drainage structure countermeasure, D 3f, had the highest crash modification factor, it would be reasonable to require new driveways to be constructed so that they are traversable. This should include all new driveways, including residential driveways. This recommendation combined with a HSIP warrant to identify and treat potentially hazardous locations could reduce the risk of fatal crashes on rural two-lane roads.<BR><BR>Currently, NCDOT does not have a complete list of crash reduction factors for all countermeasures implemented. This process can be modified and used to develop a more complete list of crash modification factors. Since the process has already been developed through this project, the only components needed to apply this methodology to other situations is the crash selection process. Once the crash reduction process is developed, then the engineers would complete the same process and analyses that were used in this project. The resulting product would be a more complete list of crash reduction factors that NCDOT could use to help prioritize safety projects.<BR><BR></FONT><FONT face=Verdana size=2>The last recommendation includes developing HSIP warranting criteria and working with the Governor's Highway Safety Program (GHSP) and law enforcement agencies to target speed enforcement. Such targeted programs could help identify locations and times where there are higher incidents of speed related crashes.<BR><BR></FONT><FONT face=Verdana size=2>This study reviewed only a select number of countermeasures and it would be preferable to evaluate more countermeasures than the 30 identified. However, the cost of developing the additional countermeasures prevented adding additional countermeasures in this study. If a similar program became standard practice during the review of all fatal crashes, then over time, a robust source of information concerning fatal crashes in North Carolina could be developed.</FONT></P>
A. D. (Tony) WyattMustan KadibhaiApril 2001 - November 2001
102
Complete
1
2002-07
3
  
321121999EnvironmentFlora and FaunaIncreased Options for Weed Management in the North Carolina Highway Wildflower Program
<P><FONT face=Verdana size=2>The North Carolina Department of Transportation (NCDOT) has implemented a highway wildflower program that now encompasses 3500 roadside acres throughout the state. Methyl Bromide has become essential in establishing these beds. However, the Environmental Protection Agency (EPA) has classified Methyl Bromide as an ozone-depleting substance, and has banned production in 2005. Research was conducted 1.) to determine if wildflowers could be established and maintained using pre-emergence (PRE) and / or post-emergence (POST) herbicides, 2.) to evaluate the efficacy of these herbicides on native vegetation, and 3.) to evaluate the efficacy of non-chemical weed control options such as cover crop plantings. <BR><BR></FONT><FONT face=Verdana size=2>Twenty-one PRE and 20 POST herbicides were evaluated on 29 wildflower species in 3 greenhouse and 2 field trials. In general, wildflowers were more tolerant to the PRE herbicides. However, no herbicide came close to Methyl Bromide with respect to safety and tolerance of all wildflower species. Field personnel must be able to select species based on weed presence and the herbicides needed to control those specific weeds without injuring the wildflowers. <BR><BR></FONT><FONT face=Verdana size=2>Based on NCDOT surveys, the 3 most problematic weeds throughout the state are vetch species, curly dock and Carolina geranium. These weeds were controlled PRE, and also POST, with Cotoran 4L, Sinbar 80WP and Velpar 75DF. However, only limited wildflower species displayed tolerance to these herbicides. None of the 29 species evaluated have tolerances to Velpar 75DF applied POST, so this treatment is not an option. Ox-eyed daisy (mature plantings of 1 year or more) and spurred snapdragon were the only wildflower species with POST tolerance to Sinbar 80WP. <BR><BR></FONT><FONT face=Verdana size=2>Greenhouse trials were initiated to see if cover crop plantings would control weeds. Rye, wheat and oats were tested on 12 weed species. None of the weeds were completely controlled, but dry weights were reduced in hairy vetch in 2 of 2 trials. Dry weights were reduced in common lambsquarter, curly dock, redroot pigweed, wild mustard, spiny sowthistly and Carolina geranium in 1 of 2 trials. Cover crops should not be considered a substitute for herbicides for weed control in wildflower beds. </FONT></P>
<P><FONT face=Verdana size=2>The NCDOT Roadside Environmental Unit can utilize these data to develop wildflower herbicide programs for any specific bed throughout the state based on weed presence. For efficient herbicide use, NCDOT field personnel must identify weeds in an accurate and timely fashion. These persons could receive training from NCSU extension faculty members, who conduct weed management workshops several times a year in various North Carolina counties.<BR><BR></FONT><FONT face=Verdana size=2>These herbicide recommendations will be incorporated into a computerized wildflower decision aid model developed by Dr. Gail Wilkerson at NCSU. A decision aid will allow interested parties to enter a number of variables (weeds, wildflowers, herbicides of interest, etc.) in order to construct a customized weed-management program for a given area. With all of the possible herbicide / wildflower combinations, a decision aid will be an efficient and necessary tool for NCDOT personnel.</FONT></P>
Charles L. TomlinsonG. Dennis PipkinApril 1999 - June 2002
102
Complete
1
2002-020
4
  
341022000Traffic ForecastingOvercoming Obstacles to the Use of Traffic Signal Detector Data for Traffic Forecasting
<FONT face=Verdana>North Carolina Department of Transportation (NCDOT) traffic engineers use inductive loop traffic detectors in order to provide efficient signal timing at signalized intersections that do not assign right-of-way under a fixed time division framework. As vehicles travel over the electrified loops, amplifiers in the signal cabinet detect changes in vehicle inductance. The controller uses this traffic demand information transmitted from the amplifiers to modify signal timing on a cycle-by-cycle basis. When the loops are working properly and the signal-timing scheme is appropriate; the result is very efficient operation of an at-grade intersection. <BR><BR></FONT><FONT face=Verdana size=2>The NCDOT Traffic Survey Unit (TSU) collects the vast majority of traffic data for the Department. Individuals and organizations are demanding ever more current, detailed, and accessible traffic data from the TSU. Unfortunately, limited human resources hamper the ability of the TSU to collect data as often, and in as many locations, as desired. In addition, signalized intersections provide additional challenges of complexity and safety to TSU personnel. The possibility of adding signal detector counts to the mix of available data is very appealing to the TSU. <BR><BR></FONT><FONT face=Verdana size=2>NCDOT and ITRE have conducted a limited study into the use of advanced detector amplifiers for traffic counting purposes. With the cooperation of Reno A&amp;E, a signal electronics vendor, NCDOT and ITRE tested standard and advanced (dual-output) detector amplifiers in a variety of settings in Wake County.<BR><BR></FONT><FONT face=Verdana size=2>This research project is designed to see if a) the loop counts are or could be of a reasonable quality to have uses within and beyond the NCDOT Traffic Survey Unit, and b) to incorporate this loop data into signal design, construction, operations, and maintenance procedures. <BR><BR></FONT><FONT face=Verdana size=2>This report provides a brief primer on traffic operations engineering, since it is important to understand, at least in a general way, how signals are timed and what role inductance loop detection plays. The report continues with some background information regarding the controllers and detectors that are used to implement traffic operations in the field. The document also contains a brief literature review, describing some efforts by other areas in this regard. The report continues with a summary of the user¿s workshop held in 1999. The report then offers a detailed summary of the field experiments conducted in 1999, 2000, and 2001. The paper then provides specific recommendations for implementation, grouped by category. The recommendations apply to both NEMA TS-1 and TS-2 cabinets. </FONT>
<P><FONT size=2><FONT face=Verdana>Regarding general recommendations concerning loop accuracy, we identified a high level of congruence between manual counts and the 6' x 6' stretch loops during our field tests. Therefore, <STRONG>our overall recommendation is to begin using stretch (far) loops for traffic counts by rewiring cabinets and installing detector amplifiers with count outputs on an as-needed basis.</STRONG> We identified a substantial variation between the traffic detector data from quadrupoles (tied to detector amplifiers that can detect inductance changes) and the manual count-defined ¿ground truth¿ in several cases, so<STRONG> we do not recommend the use of quadrupoles for counts at this time</STRONG>. As noted in the cabinet wiring recommendations later, the Department does not need to replace every detector amplifier with count-output units; rather, it can simply swap them out as needed for counts. Finally, given that we observed essentially no variation between rhombus, diamond, and square shaped loops during our 2001 field investigation, <STRONG>we recommend that North Carolina retain the use of rectangular (square) 6' x 6' loop shapes.</STRONG></FONT></FONT></P>
Mustan KadibhaiJuly 1999 - June 2001
102
Complete
1
2001-001
5
  
361042000Pavement & MaintenancePavement PerformanceUse of Falling Weight Deflectometer Multi-Load Data for Pavement Strength Estimation
<P><FONT face=Verdana size=2>The objective of this study is to develop a mechanistic-empirical method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for asphalt pavements that uses multi-load level FWD deflections has been developed using these relationships. The verification study was conducted using field data. The results indicate that the proposed procedure can estimate the base and subgrade layer conditions. It was found from the study for the nonlinear behavior of a pavement structure that an FWD test with a load of 12 kip or less does not result in any apparent nonlinear behavior of the subgrade in aggregate base pavements. The study also indicated that the deflection ratio obtained from multi-load level deflections may predict the type and quality of the base/subgrade materials. With regard to the condition assessment of the asphalt concrete (AC) layer, the AC layer modulus and the tensile strain at the bottom of the AC layer were found to be better indicators than deflection basin parameters.<BR><BR></FONT><FONT face=Verdana size=2>The procedures for performance prediction of fatigue cracking and rutting were developed for flexible pavements. The drastically increasing trend in fatigue cracking with time may not be predicted accurately using the proposed procedure. Such trends may be due to the environmental effects and the inconsistent distress measurements. Predicted rut depths using multi-load level deflections show good agreement with measured rut depths over a wide range of rutting. However, the procedure using single load level deflections consistently underpredicts the rut depths. It was concluded that the rutting prediction procedure using multi-load level deflections can estimate an excessive level of rutting quite well and, thus, improve the quality of prediction for rutting potential in flexible pavements.</FONT></P><BR><br><P><FONT face="Verdana, Arial, Helvetica, sans-serif" size=2><FONT face=Verdana size=2>The layer condition assessment procedure and the remaining life prediction algorithms developed in this project were incorporated into APLCAP (Asphalt Pavement Layer Condition Assessment Program) version 2.0, the VisualBasic program developed under the NCHRP 10-48 project.</FONT></FONT></P>
<P><FONT face=Verdana size=2>This study discusses the use of multi-load level FWD deflections for layer condition assessment and performance prediction in flexible pavements. To simulate the actual pavement responses, the dynamic finite element program in conjunction with the stress-dependent soil model was developed as a forward modeling of pavement structure. Based on the synthetic database developed from a forward modeling program, an attempt was made to establish the pavement response models for specific types of distress. To estimate layer condition and remaining life of flexible pavements, the multi-load level deflection analysis methods were developed using pavement response models and pavement performances obtained from the various field databases. Based on the study, the following conclusions may be drawn:</FONT><BR></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>The deflection basin parameters and critical pavement responses can be used to determine the strength of base and subgrade materials of a flexible pavement. A 12 kip of FWD load level, used as the maximum load level by the NCDOT, seems not large enough to improve the accuracy in assessing base and subgrade layer condition.</FONT> <BR></FONT><br><LI><FONT face=Verdana size=2>The predicted elastic modulus of the AC layer, Eac, and critical pavement responses, ?ac and d?ac, are capable of estimating the current condition of the AC layer. </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Results from the study for nonlinear behavior of a pavement structure indicate that the deflection ratio obtained from multi-load level deflections can predict the type and quality of base/subgrade materials.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>The performance of fatigue cracking can be predicted using the proposed procedure except for pavements with high and rapidly increasing cracking in wet freeze regions. Better prediction was achieved by employing climatic factors to this prediction algorithm.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>The proposed procedure for rutting performance prediction was found to be accurate in estimating the actual rutting performance. The rutting performance prediction was validated with data collected from pavement sections in the LTPP database. Research efforts also were concentrated on accurately predicting the individual layer rutting.</FONT> </FONT></LI></OL><br><P><FONT face=Verdana size=2>More field data are needed to further validate the proposed procedures. The traffic monitoring data, climatic information, and detailed data on pavement materials should be collected by well controlled technique. The FWD load levels used in this study are limited up to 16 kip. The greater FWD load level deflection data is necessary in some strong pavements to yield more accurate and reliable prediction of pavement performance. Additional research effort is needed to investigate the effect of shift factors in the pavement performance models on the proposed procedures.<BR><BR></FONT><FONT face=Verdana size=2>The major products from this research project are the asphalt pavement layer condition assessment and remaining life prediction procedures displayed in Figures 4.55, 5.33, and 5.34. These procedures are programmed into APLCAP (Asphalt Pavement Layer Condition Assessment Program), a VisualBasic software developed at North Carolina State University for the NCHRP 10-48 project. The resulting product is an APLCAP version 2.0, for which the operational guideline is given in Appendix C. <BR><BR></FONT><FONT face=Verdana size=2>In order for this program to be successfully implementd by the NCDOT, the program needs to be tested by PMU engineers for various field cases. Their feedback on the performance of the program is necessary to customize it to meet the needs for routine operation. Some parts of the program require further research and refinement, including: (1) traffic data analysis; (2) the effect of damage on the
Judith Corley-LayMustan KadibhaiJuly 1999 - June 2001
102
Complete
1
2002-06
6
  
362052000Facility DesignAssessing the Feasibility of Using TRANSIMS in North Carolina: The Fayetteville - Fort Bragg Case
<P><FONT face=Verdana size=2>The project assesses the feasibility of implementing TRANSIMS to accomplish regional transportation modeling in North Carolina. The main objectives of the study are:</FONT><BR></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Assess the state-of-art of TRANSIMS development</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Assess the resource requirements necessary to apply TRANSIMS</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Estimate advantages and disadvantages, costs and benefits of doing a TRANSIMS study</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Facilitate a possible future implementation of TRANSIMS in North Carolina</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>The report summarizes TRANSIMS technology, data and resource requirements, and typical output results. To gauge TRANSIMS resource requirements for a case study application, the researchers examined the City of Fayetteville and neighboring Fort Bragg Army base. In order to demonstrate TRANSIMS and compare it to traditional techniques, the research team developed interesting analogs with CORSIM and Transplan for corridor and area-traffic analysis. An Internet-based assessment tool generalizes the benefits and resource requirements of TRANSIMS for the Fayetteville-Fort Bragg case study, and summarizes the project findings. The research finds that Fayetteville and Fort Bragg offer excellent technical opportunities to test prototype TRANSIMS methodology. However, personnel availability and other resource obligations at NCDOT necessitate deferring implementation of TRANSIMS to a future time.</FONT></P>
<P><FONT face=Verdana>During the course of this research project the team examined specific traffic problems concerning the Fayetteville-Fort Bragg case, as well as the overall feasibility of using Fayetteville and Fort Bragg in a TRANSIMS Early Deployment Project. Regarding the TRANSIMS EDP the following recommendations are made:</FONT> </P><br><UL><br><LI><FONT size=2><FONT face=Verdana>North Carolina should not develop a TRANSIMS EDP grant application until NCDOT management approves budget and other resource expectations.</FONT> </FONT><BR></LI><br><LI><FONT size=2><FONT face=Verdana>The Fayetteville Area Metropolitan Planning Organization (MPO) should have high priority as an EDP candidate.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>NCDOT should make the results of this project available to other North Carolina MPO's so that they can gauge the utility of TRANSIMS.</FONT> </FONT></LI></UL>
Mustan KadibhaiJuly 1999 - June 2000
102
Complete
1
2000-05
7
  
363062000Performance Evaluation of Fine Graded Superpave Mixtures for Surface Courses
<P><FONT face=Verdana size=2>Strategic Highway Research Program A407, "The Superpave Mix Design Manual for New Construction and Overlays" recommends that aggregate gradations pass below the restricted zone as traffic level increases. The aggregate gradation curve of most of the SUPERPAVE mixes used today, especially in the southeast region of the U.S., follows a typical "S" shape with fines lying slightly below the restricted zone. Such a gradation yields a relatively coarse mix; however, the use of gradation with fines slightly above the restricted zone is technically acceptable according to SHRP specifications. Since such a mix is similar to the I-1 or I-2 surface mixture used by the NCDOT for surfacing of the secondary roads, it will be more economical as well as more amenable to acceptance by field engineers. The use of natural sand will reduce the build up of fines in the stone quarries and encourage the use of reclaimed asphalt pavement (RAP) material.<BR><BR></FONT><FONT face=Verdana size=2>This study investigated the use of natural sand in the fine and coarse gradations for the surface course mixtures. The mixtures were designed using the SUPERPAVE mix design approach and were evaluated for their performance in terms of resistance to rutting, fatigue, and moisture damage. In addition, the accelerated performance of these mixtures was also evaluated using the Asphalt Pavement Analyzer (APA).<BR><BR></FONT><FONT face=Verdana size=2>The following are the specific objectives of the proposed study:</FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2><FONT face=Verdana size=2>Study the aggregate gradation curves and investigate the use of natural sand in the fine and coarse gradations for the Surface Course mixtures.</FONT> <BR></LI><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Design the mixtures using the SUPERPAVE mix design approach and conduct testing of the selected asphalt mixtures, including the SUPERPAVE performance tests to evaluate their performance in terms of resistance to rutting, fatigue, and moisture damage.</FONT> <BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Compare the accelerated performance test results of the selected asphalt mixtures using the Asphalt Pavement Analyzer (APA).</FONT> </LI></OL></FONT>
<P><FONT face=Verdana>It can be concluded from the test results that:</FONT></P><br><OL><br><LI style="FONT-FAMILY: Verdana"><FONT face=Verdana><FONT face=Verdana size=2>Maximum size of aggregate and type of gradation influence the performance of mixtures containing natural sand.</FONT> </LI><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>The performance of 12.5mm mixtures, in terms of fatigue and rutting, is not adversely affected by incorporation of natural sand in the mixture gradation.</FONT> <BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>The rutting performance of 9.5mm mixtures is not affected by the addition of natural sand, while the fatigue life of these mixtures is adversely affected. The 9.5mm mixtures containing natural sand have 50% to 70% of fatigue life of the mixtures made with manufactured sand.</FONT> <BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>The rutting test results indicate that the minimum service life of all the mixtures is about 3 million ESALs, while the minimum fatigue life is to the tune of approximately 1 million ESALs. Therefore, it is quite evident that even 9.5mm mixtures containing natural sand can adequately serve as a surface course for the low volume secondary roads.</FONT> <BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>The fatigue life of a given pavement structure is a function of the thickness of the asphalt concrete layer; thicker the asphalt concrete layer, higher the fatigue life. Therefore, an increase in thickness of 9.5mm mixtures containing natural sand may improve the fatigue life to a desired level.</FONT> <BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>The mixtures containing natural sand exhibit relatively higher moisture susceptibility.</FONT> <BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>The GLPA test is conducted at the compaction temperature (approximately 150oC) at which the behavior of the mixtures could be significantly different from the behavior at the maximum service temperature of 60oC. Furthermore, standard protocols call for APA tests to be conducted on specimens compacted to approximately 7% air voids and at maximum service temperature of the performance graded asphalt, i.e. 64oC. On the other hand, the shear tests are conducted on specimens compacted to Ndes and at 54oC. The discrepancy in these test conditions may obscure a meaningful comparison of the performance of mixtures as evaluated by these tests.</FONT></LI></OL><br><P><FONT face=Verdana size=2>This study has provided an objective evaluation of the Superpave mix design for mixtures containing natural sand. The results provide guidelines for designing such mixes and allow NCDOT to develop and utilize relatively economical Superpave surface course mixes for secondary roads.</FONT></P></FONT>
Mustan KadibhaiJuly 1999 - June 2001
102
Complete
1
2002-05
8
  
364022001Structures & ConstructionMiscellaneousGeogrid Reinforcement of Piedmont Residual Soil
<P><FONT face=Verdana size=2>Soil-geosynthetic composites such as those used in Mechanically Stabilized Earth (MSE) retaining walls and embankments are experiencing widespread use, particularly in transportation applications. These structures offer substantial economic and, in some cases, performance advantages over traditional options such as reinforced concrete gravity or cantilever walls. Continued growth in the use of MSE walls, particularly in critical applications such as bridge abutments, is anticipated.</FONT></P><br><P><FONT face=Verdana size=2>Several methods for designing these structures are currently in use. Two commonly used design guidelines are published by the National Concrete Masonry Association (NCMA, 1996) and the American Association of State Highway and Transportation Officials. The NCMA guidelines are followed primarily within the private sector; the AASHTO specifications are employed in the public sector. The successful application of these or any of the other design guidelines may be distilled to two concepts, (1) proper assessment of the anticipated loading conditions and (2) proper characterization of the load transfer mechanisms between the components of the MSE systems (backfill soil, reinforcing materials, and fascia units). This research project addresses issues related to the second concept. More specifically, the research examines the interactions and load transfer mechanisms between the backfill soil and reinforcing materials.<BR>The economic advantage of MSE walls is markedly increased if on-site soils are used as the backfill material in the reinforced zone. Ideally, this backfill material is relatively clean (e.g., limited fines content) and cohesionless. Practically, this is not often available on-site. The potential economic benefit of using "lower quality", on-site material in MSE retaining wall applications is substantial. Using on-site material would eliminate the time and expense associated with identifying and transporting select fill.</FONT></P><br><P><FONT face=Verdana size=2>This research examined the suitability of "lower quality" backfill soil by studying the load transfer mechanisms between representative soils and geosynthetic reinforcing materials. The primary method of studying this interaction was via a series of "pullout" tests as described in subsequent sections of this report.</FONT></P>
<P><FONT face=Verdana size=2>The following conclusions are based on the activities performed during this research program. It is important to note these conclusions are based on research performed with four specific geosynthetic reinforcing materials embedded in two types of Piedmont residual soil. While certainly representative of overall behavior, the extension to general conclusions for all geogrid products or reinforced soil types may not be appropriate.</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>A large database of soil-geosynthetic reinforcement interaction behavior has been developed. This data is particularly relevant to the work conducted by the NCDOT as it uses local, Piedmont residuum.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Parametric studies have been performed to examine the importance of soil type, reinforcement type, and confining pressure on the load transfer mechanisms of geosynthetic-reinforced soils.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>The results of this study indicate that geotextile reinforcing materials may be a better choice than geogrid materials, particularly if minimizing displacement is an important performance consideration.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Based on measurements of load and displacement, the use of "lower quality" soils appears feasible.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>Based on the results of this research program, the following recommendations are made:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>For temporary earth retaining structures, it is feasible to use "lower quality" backfill in the reinforced zone. Material that satisfies the Class II - Type 2 classification in Section 1016-3 of the NCDOT Standard Specifications for Roads and Structures may be used provided the material is placed and compacted properly. As with virtually all projects employing earth as an engineering material, proper placement is absolutely critical if desired performance is to be achieved.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>It appears that the geotextile products may be the better choice of geosynthetic reinforcing material, provided the confining pressure is sufficiently large.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>The next appropriate step is to extend this laboratory-based study to the field. This may be achieved by constructing and monitoring prototype-scale temporary retaining walls either on the UNC Charlotte campus or at a more desirable location for the NCDOT personnel. These walls should be built using the same types of soil as used in this research program (Class II - Type 2) and be reinforced with, as a minimum, a representative variety of geotextiles. Performance monitoring should focus primarily on deformations (both horizontal and vertical) and should be made throughout the construction process and for at least 18 months afterward. At that point, the walls should be loaded to failure (destructive testing) to glean as much design and performance information as possible.</FONT> </FONT></LI></UL>
Mohammed MullaMrinmay "Moy" BiswasJuly 2000 - June 2001
102
Complete
1
2002-02
9
  
365032001Pavement & MaintenanceAsphalt Mix DesignEvaluation of the Effects of Mixture Properties and Compaction Methods on the Predicted Performance of Superpave Mixtures
<P><FONT face=Verdana size=2>The Superpave volumetric design method contains no strength or 'proof' test for quality control and quality assurance of mixtures. Accelerated wheel tracking systems, such as the Asphalt Pavement Analyzer (APA) and the NCSU Wheel Tracking Device (WTD) may fulfill the need for a relatively simple and inexpensive performance test. It is imperative that the predictability of these test systems should correlate with the field performance. Moreover, several compaction methods are used to fabricate specimens for performance testing in the laboratory. The compaction methods adopted in the laboratory are expected to simulate the properties of the pavement in the field. It is essential that the laboratory compaction of specimens should be a true indicator of field performance. So, the effects of different compaction methods on the performance of mixtures have been investigated in this study. Laboratory compaction methods such as Superpave Gyratory Compaction (SGC) and Rolling Wheel Compaction (RWC) were compared with the field compaction. Four field sites had been selected for this purpose. The mixtures were identified as Auburn Coarse, Auburn Fine, Charlotte and Kinston. The Auburn mixtures were 12.5mm mixtures whereas the Charlotte and the Kinston mixtures were 9.5mm mixtures. The performance parameters of the mixtures include fatigue and rutting distresses. Various performance evaluation tests were conducted on the field cores and specimens fabricated using the Superpave Gyratory Compactor (SGC) and Rolling Wheel Compactor (RWC). Performance evaluation was done using test systems such as Shear tester, Asphalt Pavement Analyzer (APA) and NCSU Wheel Tracking Device. <BR><BR>The analysis of test results indicate that the laboratory compacted mixtures tend to be superior in their performance than the field cores. The mixtures compacted using the SGC and the RWC have higher stiffness values and lower shear strain values than the field cores. The Rolling Wheel Compaction (RWC) seems to simulate field compaction better than the SGC. The mixtures, which failed to satisfy the RSCH test criteria, had rut depths greater than 0.5 inch, as measured by the APA and NCSU WTD. The mixtures that passed the RSCH tests had rut depths less than 0.5 inch. The APA test and the NCSU WTD test can be used as a simulator to examine the rutting susceptibility of a mixture. It is suggested that a rut depth of 0.5 inch could be prescribed in the APA test and the NCSU WTD test as "pass/fail" or "go no-go" criteria.</FONT></P>
Mustan KadibhaiJuly 2001 - June 2002
102
Complete
1
2002-030
10
  
381012001Structures & ConstructionBridge DesignAnalysis of an Instrumented Jointless Bridge
<P><FONT face=Verdana size=2>There are three primary objective of the research project. The first is to validate analysis and design assumptions for simply supported girders, compatibility of deformation between girders and link-slab, force-deformation behavior and strain state in link-slab under prescribed end-rotations, and link-slab softening. The second objective is to investigate limit-states design methods (methods for assessing firder end rotations and allowable link-slab reinforcement strain for various load conditions) and simplified design procedures for link-slab bridges. Live load testing, long term live load testing, and seasonal thermal testing will all be done on the bridge. The final objective is to develop a guide for long-term monitoring.</FONT></P>
Mrinmay "Moy" BiswasJuly 2001 - June 2002
102
Complete
1
2002-22
11
  
401042001Pavement & MaintenancePavement PerformanceA Mechanistic Approach to Evaluate Contribution of Prime and Tack Coat In Composite Asphalt Pavements
<P><FONT face=Verdana size=2>This investigation was undertaken to develop a mechanistic design procedure for selection of tack and prime coat type in relation to traffic loading, pavement temperature and the AC overlay required thickness. The methodology used in this study to compare the performance of different tack and prime coats required the development of a 3-D computer program that takes into account the horizontal shear stresses induced on the pavement surface due to vehicle braking effects (acceleration and deceleration). Taking into account the induced shear loading, the shear stresses at the interface layers were computed. Next, these shear stresses were compared to the bond strength of the tack or prime coat under consideration. This research study provides a methodology and design guide based on mechanistic analysis to select appropriate tack or prime coat for given field conditions. Based on the AC layer thickness a suitable tack or prime coat can be chosen (or vice versa in some cases) to minimize the delamination distress.</FONT></P>
Mustan KadibhaiJuly 2000 - December 2003
102
Complete
1
2004-05
12
  
402052001EnvironmentErosion and Turbidity ControlMeasures to Reduce Erosion and Turbidity in Construction Site Runoff
<P><FONT face=Verdana size=2>An evaluation of polyacrylamides (PAM) for both erosion and turbidity control for construction sites was conducted in both the laboratory and the field. A laboratory screening was conducted for 11 PAMs on 13 sediment sources from North Carolina Department of Transportation (NC DOT) construction sites around North Carolina. In addition, a field test of two PAMs at two rates, with and without straw mulch and seeding, on a 2:1 fill slope, a 4:1 cut slope, and a 4:1 fill slope were performed. The results indicate that there is no one PAM that is effective for turbidity reduction on all sediment sources, but several are promising for many soils. Superfloc A-100 ranked among the top three flocculants for 10 of 13 sediment sources. Some PAMs are equally effective but at different doses, some as low as .075 mg/L, or a few grams per 1,000 ft3 of water. The differences between PAMs in reducing turbidity were clearest shortly after mixing the PAM and soil (30 sec). These turbidity differences were usually maintained 30-60 minutes after mixing, but allowing the soil/water mix to settle for 24 hours reduced or eliminated the differences. Tests of PAM with and without mulching on 2:1 slopes at NC DOT construction sites failed to show a significant reduction in turbidity or erosion. Erosion rates were 20 times greater on bare soil plots after the first seven events, with or without PAM, compared to those mulched with straw and seeded to grass. During the eighth and last event, in which over 6 cm of rain was recorded, rates of over 50 tons/ha were recorded for a single, intense storm event for the bare soil plots compared to 3-9 tons/ha on the mulched/seeded plots. PAM at the highest rate (11 kg/ha) was effective in reducing erosion and turbidity on the 4:1 cut slope with a clay loam texture but the effect declined with each storm event. On the sandy 4:1 fill slope, there was no evidence of PAM effects, even at 20 kg/ha. PAM was effective in flocculating turbid water pumped from a borrow pit but turbulence within the basin tended to keep the flocs from settling.</FONT></P><BR><br><P>&nbsp;</P>
<P><FONT face=Verdana size=2>Applying PAM to bare soil surfaces to reduce erosion appears to have two limitations. One is the slope steepness, since we found no evidence of PAM effects on a 2:1 slope but some erosion and turbidity reductions on a 4:1 slope. Since PAM is known to only influence the surface 1-2 mm of soil by maintaining structure, the erosive forces on steep slopes apparently remove this layer relatively quickly during the first storm. Exactly where the breaking point is for PAM to be effective will likely be site specific. The second limitation is in the longevity of treatment effects. There is some evidence that these disappeared in the field after several rainfall events. This was further corroborated in our rainfall simulation tests. Again, the longevity of PAM effectiveness will be specific to the application, site characteristics, and rainfall patterns. Higher rates of PAM may be more effective for longer periods. In most cases, the mulch and seed treatment was usually so effective in reducing erosion and turbidity that the PAM treatments did not provide any additional benefit to water quality.<BR><BR></FONT><FONT face=Verdana size=2>PAM was found to be effective in reducing turbidity produced from a wide range of sediment sources. A number of reactions were observed, including several sediment sources which did not respond to the PAMs in our tests. However, most of the sediments had relatively straightforward, linear reductions in turbidity with increasing PAM concentrations. In most cases, 0.5-1.0 mg/L was sufficient to achieve maximum turbidity reduction. It appears that PAM is effective for turbidity caused by a majority of sediments from around North Carolina.<BR><BR></FONT><FONT face=Verdana size=2>We have not developed clear relationships between sediment and PAM properties and turbidity reduction at this point. Work will continue on this topic with the goal to develop a guide to PAM selection based on one or more sediment properties. <BR><BR></FONT><FONT face=Verdana size=2>Recommendations to reduce erosion and turbidity in construction site runoff include:</FONT><BR></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Mulching and seeding is extremely effective in stopping erosion - this practice should be implemented after soil disturbance as quickly as feasible.</FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>PAM use for erosion control on bare soil has potential, but may be limited to low slopes for short periods.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>PAM is effective in reducing turbidity caused by most sediment sources tested and should be included as part of sediment control systems in the future.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>PAMs will need to be selected for site-specific conditions. However, some PAMs are useful for a wider array of sediments than others.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>PAMs may not be effective in some cases and may need to be augmented or substituted with inorganic salts, coagulants, or other materials.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Flocs formed after PAM applications may require filtration or relatively calm water in order to settle. Where pumping is already in place, such as at borrow pits, filtering systems would be relatively simple to devise or obtain.</FONT> </FONT></LI></OL>
Don LeeG. Dennis PipkinJuly 2000 - June 2002
102
Complete
1
2002-023
13
  
403062001Pavement & MaintenanceVegetation Management and RoadsideVegetation Management under Guardrails for North Carolina Roadsides
<P><FONT face=Verdana size=2>During the spring of 1998 the North Carolina Department of Transportation (NCDOT) began a guardrail installation initiative which required over 1000 miles of newly installed median guardrail on North Carolina's major thoroughfares. The implementation of this program increased workloads and maintenance costs for the NCDOT. Turfgrasses currently used under and adjacent to guardrails include primarily 'Kentucky-31' tall fescue (<EM>Festuca arundinacea Schreb</EM>.) and bahiagrass (<EM>Paspalum notatum L.</EM>). Unfortunately, these species possess high maintenance requirements. Alternative species such as centipedegrass (<EM>Eremochloa ophiuriodes</EM>) or zoysiagrass (<EM>Zoysia japonica</EM>) would reduce maintenance costs on these thoroughfares due to lower maintenance requirements. Centipedegrass is a minimal input turf species requiring no more than 44 lb N/a/yr and infrequent mowing. It is adapted to a wide range of soil conditions, but grows best in sandy, acidic soils which make it ideal for increased use along roadsides. Further, these species improve motorist's visibility due to inconspicuous seedheads resulting in safer, more economical, and aesthetically pleasing roadsides. In a majority of these situations, centipedegrass was sodded into existing roadside vegetation which included turf species such as bahiagrass or tall fescue. <BR><BR></FONT><FONT face=Verdana size=2>The purpose of this research was to determine management plans for these areas where centipedegrass or zoysiagrass was sodded into existing vegetation. Management plans included herbicide and plant growth regulator tolerance as well as practices to transition the roadside to centipedegrass or zoysiagrass in an effort to achieve a monoculture turfgrass stand. Experiments included centipedegrass tolerance to herbicides and plant growth regulators applied at seeding and soon thereafter, centipedegrass survival when subjected to various fertility regimes, zoysiagrass versus centipedegrass establishment from sod under roadside conditions, among others.</FONT></P>
Mustan KadibhaiJuly 2000 - June 2003
102
Complete
1
2004-02
14
  
404072001EnvironmentWater Quality and Pollutant DischargeEvaluating Best Management Practices (BMPs) for Treating Stormwater and Wastewater from North Carolina Highways, Industrial Facilities, and Borrow Pits
<P><FONT face=Verdana size=2>In June, 1998, the Division of Water Quality of the NC Department of Environment and Natural Resources issued a National Pollution Discharge Elimination System (NPDES) Permit (no. NCS000250, for the period June 8, 1998 to May 31, 2003) to NCDOT authorizing the discharge of borrow pit wastewater and stormwater associated with industrial activities. The permit outlines requirements such as <EM>Stormwater System Inventory and Prioritization</EM>, <EM>BMP Retrofits</EM> and <EM>BMP Toolbox</EM> for Roadway Drainage &amp; Construction Sites, Industrial Activities, and Borrow Pit/Waste Pile Activities. In addition, the permit details specific record keeping and reporting requirements. <BR><BR></FONT><FONT face=Verdana size=2>This research project will provide NCDOT assistance in meeting the following permit requirement: ¿Analytical monitoring of (1) ferry facility, (3) industrial facilities, (2) borrow pits, and (4) highways.¿ This research will also evaluate the structural Best Management Practices (BMPs) for treating runoff from all 20 sites. <BR><BR></FONT><FONT face=Verdana size=2>Data elements to be collected include storm criteria and number to be sampled, borrow pit sampling, monitoring description, QA/QC measures, covariates (land use characteristics and tracking) and data analysis. </FONT></P>
G. Dennis PipkinJuly 2000 - June 2005
102
Complete
1
2006-05
15
  
405082001Traffic & SafetyTraffic ForecastingUsing GIS-Based Property Tax Data for Trip Generation
<FONT face=Verdana>This project assesses the feasibility of using statistically clustered property tax data instead of windshield survey data for input into the Internal Data Summary (IDS) trip generation model used by the North Carolina Department of Transportation. The report summarizes the clustering analysis and its data requirements. To gauge clustering resource requirements for a case study application, NCSU researchers examined the town of Pittsboro. Comparing the traffic flow outputs of the traditional modeling techniques and those resulting from the use of the clustering method to 56 ground count stations, the research finds that clustering and traditional methods yield similar results. The main benefit resulting from the use of the clustering technique is an 85% reduction in work-hours required to gather the input data. The major drawback is that advanced statistical training is required to implement the technique.</FONT>
Mustan KadibhaiJuly 2000 - June 2002
102
Complete
1
2002-28
16
  
406092001EnvironmentWetlands MitigationMethodology to Assess Soil, Hydrologic, and Site Parameters that Affect Wetland Restoration
102
Complete
0
2003-06
17
  
407102001Flora and FaunaDistribution of Freshwater Mussel Populations in Relationship to Crossing Structures
<P><FONT face=Verdana size=2>More than 2/3 of the freshwater mussel types in NC are threatened if not endangered. This statement may be slightly misleading since the overwhelming majority of the NC mussel population is of the species Elliptio complanata. Mussels provide a natural water filter system and it¿s because of this that they are particularly vulnerable to contaminants in the water. Because mussels are vulnerable to water contamination, the extent of their presence is an indicator of water quality. Their natural water filtering system is also helpful in maintaining water quality. </FONT></P><br><P><FONT face=Verdana size=2>This research project is significant since it will provide the information needed to determine if additional steps should be taken in the construction and maintenance of crossing structures to minimize their impact on mussel populations.</FONT></P><br><P><FONT face=Verdana size=2><STRONG>Objectives: </STRONG></FONT></P><br><P><FONT face=Verdana size=2>The main objectives of the research project are:</FONT></P><br><UL><br><LI><FONT face=Verdana size=2>To determine the distribution of freshwater mussel species above and below crossing structures. </FONT><br><LI><FONT face=Verdana size=2>To quantify the abundance of freshwater mussel species. </FONT><br><LI><FONT size=2><FONT face=Verdana>To measure the affect of the crossing structures on mussel distribution and abundance.</FONT> </FONT><br><LI><FONT face=Verdana size=2>To identify specific attributes about road crossing structures that my be altering the distribution and/or abundance of freshwater mussels. </FONT></LI></UL>
Gordon CashinG. Dennis PipkinJuly 2000 - December 2002
102
Complete
1
2003-02
18
  
441092001Methodology to Assess Soil, Hydrologic, and Site Parameters that Affect Wetland Restoration
<P><FONT face=Verdana size=2>Juniper Bay was developed for agriculture several decades ago and currently has about 300 ha of drained and intensively managed agricultural land that is not jurisdictional wetland due to its status as prior converted agricultural land. The drainage system in Juniper Bay not only removes excess surface and ground water, but it directs runoff to a different location in the watershed than under previous natural conditions. The overall goal of the research is to evaluate the strategy and performance of the restoration of wetland functions in Juniper Bay and to test alternative restoration methods.<BR><BR>The restoration efforts will include:</FONT></P><FONT face=Verdana size=2><br><UL><br><LI></FONT><FONT size=2><FONT face=Verdana>plugging or filling the drainage ditches as necessary to restore historical hydrologic functions and the directions and rates of surface and subsurface runoff</FONT> </FONT></LI><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>re-establishing the forest community in accordance with community types located in the reference ecosystem</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>soil management as needed to assist in hydrologic function restoration, forest community establishment, and nutrient cycling processes.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>This research will evaluate whether these strategies are sufficient to restore appropriate wetland functions in Juniper Bay, and will identify other factors and methods that must be addressed in implementing wetland restoration in depressional wetlands that have been converted to agriculture.<BR><BR></FONT><FONT face=Verdana size=2>The objectives of this research are to:</FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Document the variability in the properties of soils and sediments and the water table regime across Juniper Bay and the reference bay that will affect restoration success.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Determine current groundwater flow paths and water table regime both inside and outside Juniper Bay, and identify a strategy for hydrologic restoration.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Assess the recovery rate of key hydrologic, biogeochemical, and plant community functions that are necessary for a sustainable wetland ecosystem.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Assess the usefulness of reference ecosystems for defining required hydrologic and soils factors and target vegetation composition necessary for long-term restoration success.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Identify soil chemical and physical properties and hydrologic requirements for optimum growth of Carolina Bay vegetation.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Determine the effect of tree species type and diversity for achieving sustainable growth of desired vegetation and soil characteristics in the restored Carolina Bay.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Test different restoration methodologies.</FONT> </FONT></LI></OL>
Jim HauserG. Dennis PipkinJuly 2000 - June 2003
102
Complete
1
2003-06
19
  
461112001EnvironmentWetlands MitigationEcological Assessment of a Wetlands Mitigation Bank
<P><FONT face=Verdana size=2>Highway construction often impacts ecology by causing unavoidable losses of wetland areas. Increasingly, wetland losses are being mitigated by creating ¿Banks¿ with ¿wetland deposits¿ in advance of the wetland destruction caused by roadway construction. The Tulula Wetland Mitiagation Bank (located in Graham County, west of Asheville on the Tennessee/North Carolina State border) was created to offset impacts of highway projects in western North Carolina, particularly in the Little Tennessee River basin. This wetland is considerably different from most North Carolina wetland mitigation banks (which are primarily coastal) in terms of hydrology, agronomy, flora and fauna.<BR><BR></FONT><FONT face=Verdana size=2>The goal of this research project is to document the ecological success of the wetlands at Tulula in response to restored hydrology, soils, and vegetation. Data will provide NCDOT an ecological assessment that will be useful for evaluating other wetland restoration projects.</FONT></P><BR><br><P><FONT face=Verdana size=2><FONT face=Verdana size=2><STRONG>Objectives:&nbsp;<BR><BR></STRONG></FONT><FONT size=2><FONT face=Verdana><STRONG>&nbsp;</STRONG>The main objectives of the research project are: </FONT></FONT></P><BR><br><OL><BR><br><LI><FONT face=Verdana size=2>To determine the success of stream realignment (i.e. relocating the stream) by evaluation the geomorphology (geometric configuration of the geology) of the new channel before and after water is introduced. </FONT><BR><BR><br><LI><FONT face=Verdana size=2>To evaluate changes in ecosystem structure and function in response to a higher water table as the result of site hydrology restoration. </FONT><BR><BR><br><LI><FONT face=Verdana size=2>To evaluate wildlife (frog, salamanders) use of the site in response to a higher water table as the result of site hydrology restoration. </FONT></LI></OL></FONT>
Gordon CashinG. Dennis PipkinJuly 2000 - June 2002
102
Complete
1
2002-27
20
  
462122001Effects of Shading from Bridges on Estuarine Wetlands
<P><FONT face=Verdana size=2>Salt and brackish-water marshes are integral parts of the coastal ecosystem, performing important nutrient cycling and hydrologic functions as well as providing habitat and breeding grounds for many coastal species. As coastal populations increase, so does the need for an improved and more extensive infrastructure including bridging across estuaries and marshes. Mitigation is now required to alleviate the effects of shading from bridges spanning marshes. However, little research has been conducted to actually quantify the effects of bridge height and width on marsh productivity. The objectives of this research are to 1) determine the effects of bridge height and width on marsh productivity and function by directly assessing light attenuation under bridges, 2) to determine the effects of shading on the dominant salt-marsh plant species, and 3) to compare benthic invertebrate communities beneath seven highway bridges with marshes outside of bridge-affected areas (reference marshes). </FONT></P><br><P><FONT face=Verdana size=2>Photosynthetically-available light was measured. Plant samples were clipped, dried, and weighed to determine above-ground biomass, average stem height, number of stems, number of flowers, and basal area. Soil cores were taken to a depth of 30 cm. To determine soil carbon, nitrogen, and below-ground biomass. Results indicate that both bridge height and width influenced the degree to which shading by bridges affected the underlying vegetation. All plant variables measured showed a strong bridge effect at height-to-width (HW) ratios less than 0.5 and light measurements less than 250 umol m -2s-1 under the bridges. At a HW ratio of 0.7, bridge effects were still detected, although they were greatly diminished. Of thirty-two comparisons between areas under and outside the influence of bridges having HW ratios greater than 0.7, only four significant differences were detected. Secondary production was also clearly correlated with the bridge HW ratio, (r 2=.95). Low bridges, with HW ratios of &lt;0.7 and light attenuations of &lt;260 mol m -2s-1 (photosynthetic photon flux units), had benthic invertebrate densities and diversity that were significantly lower than reference marshes. Density of benthic invertebrates at low bridges was 25-52% (29,685-72,920 organism/m 2) of densities measured in adjacent reference marshes (119.329-173,351 organism/m 2). Likewise, there were fewer taxa under low bridges (5.8/11.35 cm 2 core) as compared to the reference marshes (9.0/11.35 cm 2 core). Densities of numerically dominant taxa (oligochaetes, nematodes) as well as surface- and subsurface deposit feeders also were reduced by shading of low bridges. Decreased invertebrate density and diversity beneath low bridges was attributed to diminished above- and below-ground macrophyte biomass that presumably resulted in fewer food resources and available refuges from predators. Data indicates that shading by bridges having HW ratios above 0.7 do not adversely impact the productivity or function of the underlying marsh. The best design is a bridge greater than 9 m over the underlying marsh that is narrow enough to keep the HW ratio greater than 0.7. </FONT></P>
G. Dennis PipkinJuly 2000 - June 2003
102
Complete
1
2003-07
21
  
463132001EnvironmentFlora and FaunaAssessment of the Impact of Highway Runoff on the Health of Freshwater Mussels in NC Streams
<P><FONT face=Verdana size=2>Freshwater mussels (unionids) are one of nature¿s water filtering mechanisms and a vital component of freshwater ecosystems. Freshwater mussels also serve as a food source for a wide variety of terrestrial and aquatic animal species.</FONT></P><br><P><FONT face=Verdana size=2>Assessing the impact of road construction projects on adjacent surface waters is a complex task. Environmental impact surveys traditionally assess the presence or absence of individual species, and the potential impact of construction on species present at the construction site. Freshwater mussels are long lived; Many freshwater mussel species live more than 40 years. The presence of these long-lived animals does not necessarily reflect the viability of the population. Freshwater mussels may be present, but if their fish hosts have been displaced juvenile and adult stages of mussels, and the various stages of host fish may also be markedly different. Accurate assessment of the impact of road runoff contaminants on mussel populations requires quantification of both adult and juvenile populations.</FONT></P><br><P><FONT face=Verdana size=2>Various road construction alternatives are available to reduce the movement of rainwater into adjacent streams. Implementation of these construction strategies can add greatly to the cost of road construction. A clear understanding of the actual risk posed by these contaminants in road runoff is needed before suggesting selected site or universal adherence to these construction guidelines. </FONT></P><br><P><FONT face=Verdana size=2><STRONG>Objectives: </STRONG></FONT></P><br><P><FONT face=Verdana size=2>The main objectives of the research project are: </FONT></P><br><OL><br><LI><FONT face=Verdana size=2>To identify the contaminants in road runoff that are entering NC streams; </FONT><br><LI><FONT face=Verdana size=2>To develop non-lethal field sampling techniques for assessing the health of freshwater mussel populations; and </FONT><br><LI><FONT size=2><FONT face=Verdana>To measure the potential impact of contaminants in road runoff on mussel health.</FONT> </FONT></LI></OL>
Gordon CashinG. Dennis PipkinJuly 2000 - March 2003
1
2004-03
22
  
481142001Flora and FaunaAssessment and Prediction of the Effects of Highways on Population Ecological and Genetic Properties of Selected Faunal Groups
<P><FONT face=Verdana size=2>The focus of this study was to identify effects of roads on amphibian species that might serve as predictors of future sensitivity to habitat fragmentation. To accomplish this task, 134 sites were sampled, primarily in the Piedmont region of North Carolina, using both active and passive methods. Animals were collected at the study sites from August 2000 until December, 2002. A significant drought (a rainfall deficit of &gt;14 inches) spanned the entire study period. The low number of animals studied is likely a result of the high mortality rates and low activity levels displayed by amphibians during drought conditions. </FONT></P><br><P><FONT face=Verdana size=2>This research project provides an extensive review of the literature dealing with roads as barriers to amphibian movement. Patterns derived from the literature provide a framework for the recommendations made in the research report. Also included in the report is a description of the modeling of habitat fragmentation and barriers. This model was the framework for the interpretation of the genetic analysis, and is the focus of ongoing study.</FONT></P>
G. Dennis PipkinAugust 2000 - December 2002
102
Complete
1
2003-01
23
  
501152001Pavement & MaintenanceAsphalt Mix DesignMaterials Characterization and Performance Properties of Superpave Mixtures
<P><FONT face=Verdana size=2>The objective of this research is to characterize HMA properties, and to develop phenomenological fatigue relationships for these mixes based on various levels of strain, asphalt content, air voids content, and temperatures on superpave mixes in use in NC. The research will include laboratory investigation of 12.5mm and 19mm intermediate mixes at moderate temperatures of 15° C, 20° C, and 25° C where predominant fatigue cracking is expected to be significant. The principal work tasks to be conducted are as follows:</FONT></P><br><UL><br><LI><FONT face=Verdana size=2>Design asphalt mixes using superpave methodology using PG 64-22 binder. </FONT><br><LI><FONT face=Verdana size=2>Prepare beam, prismatic beam, and slab specimens and obtain cores. </FONT><br><LI><FONT face=Verdana size=2>Conduct flexural fatigue tests on beam specimens. </FONT><br><LI><FONT face=Verdana size=2>Conduct shear frequency sweep tests on cores. </FONT><br><LI><FONT face=Verdana size=2>Conduct axial frequency sweep tests on prismatic beam specimens. </FONT><br><LI><FONT face=Verdana size=2>Develop fatigue distress models and axial &amp; shear stiffness models. </FONT><br><LI><FONT face=Verdana size=2>Develop a pavement and overlay design procedure based on typical pavement cross-sections encountered in NC. This design procedure will account for the AC mix characteristics and the reliability associated with design traffic estimation and material characterization. </FONT></LI></UL><br><P><FONT face=Verdana size=2>The anticipated results of this research along with existing computer models will help NCDOT Engineers to predict pavement failure rates and compare with results of current design procedures to develop a better understanding of the relationship of material properties to fatigue life. A detailed outline of the design procedure will be developed through this research for new pavement design, design of overlays, for forensic analysis of premature failure and for non-compliance of job specification.</FONT></P>
Judith Corley-LayMustan KadibhaiJanuary 2001 - December 2003
102
Complete
1
2004-11
24
  
521162001Traffic & SafetyMiscellaneousA Sign Inventory Study to Assess and Control Liability and Cost
<P><FONT face=Verdana size=2>The State of North Carolina currently maintains approximately 78,000 miles of road and approximately 1 million signs. In the near future, the Federal Highway Administration (FHWA) is expected to release minimum levels for sign retroreflectivity. The pending guidelines will present several new issues to state transportation agencies responsible for sign placement and maintenance, including liability, safety issues, organizational concerns, and resource concerns such as labor and cost. To date, no one has developed a system or methodology to meet the standards on a scale as vast as that faced by NCDOT.<BR><BR>T</FONT><FONT face=Verdana size=2>he main objective of this project is to determine, quantify, and present to NCDOT alternative approaches for meeting the standard. The focus of the study is on signs; pavement markings are not being considered. In addition, this report pertains to static signs only. Changeable, temporary, and contracted signs are not considered. Finally, it is not the intention of this project to create a sign inventory, but to evaluate multiple alternatives to assist the state of North Carolina with addressing the forthcoming retroreflectivity guidelines. This project it is not inclusive of municipalities and counties; however, signs on non-state maintained roads are just as much of a concern and the standard is applicable to all signs, not only state maintained signs.<BR><BR>The current sign maintenance and inspection methods of NCDOT were observed and evaluated. A life cycle of a sign in North Carolina was created based on visits to the sign manufacturing plant in Bunn, NC, discussion with NCDOT Signing Engineers, and visits to State Highway Divisions to see storage methods and accompany an actual nighttime sign inspection.<BR><BR></FONT><FONT face=Verdana size=2>Two studies were performed in conjunction with this report to estimate the number of signs on North Carolina roads because an accurate approximation was unknown. These reports resulted in an estimate of approximately 11,300 signs on Interstate roads, 369,700 signs on primary routes and 605,000 signs on secondary routes.<BR><BR></FONT><FONT face=Verdana size=2>Research included exploring retroreflectivity and it's principles, sign types and their classifications, sign sheeting types, and software and technologies available for measurement.<BR><BR></FONT><FONT face=Verdana size=2>Using the existing literature and information collected from NCDOT meetings and observations, a preliminary list of about 30 alternatives was generated. These alternatives were presented to the NCDOT research team to retrieve comments and feedback as to which alternatives they would like to see evaluated. The meeting resulted in four alternatives, which are:</FONT></P><BR><br><OL><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Maintain nighttime visual inspection method (current method),</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Maintain nighttime inspection method with improvements,</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Implement a sign inventory management system, and</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Combination of Alternatives 2 and 3.</FONT> </FONT></LI></OL><BR><br><P><FONT face=Verdana size=2>The four alternatives were outlined and costs were generated for each one.<BR><BR></FONT><FONT face=Verdana size=2>A spreadsheet to determine the accuracy of nighttime sign inspection method was created. It was also used to calculate how many signs would potentially not be in compliance after visual inspection. It was determined that the visual inspection method produces a fairly low percentage of signs that are potentially not in compliance after the inspection. It is anticipated that the percentage of signs potentially not in
<P><FONT face=Verdana size=2>This table <A href="http://www.ncdot.org/doh/preconstruct/tpb/research/download/2001-16ObjectivesTable.doc">(click here to view table)</A> lists the desired objectives of the alternatives and indicates which alternatives meet the objective. A 'y' indicates yes an alternative meets the objective and an 'n' means no the alternative does not meet the objective. All of the objectives are congruent with the wants of the NCDOT research committee as expressed in the December 5, 2001 feedback meeting and the goals and objectives of the project.<BR><BR></FONT><FONT face=Verdana size=2>Of the objectives evaluated in the table above, one of the most important use 'includes better record keeping to defend against liability claims.' Continuing with the current method, alternative 1, is the only alternative that does not meet this objective. None of the alternatives reduce the amount of labor required, however, using the same amount or more labor may lead to reduced costs in other ways.<BR><BR></FONT><FONT face=Verdana size=2>Alternatives 2 and 4 were identified as 'yes' for generating numerical retroreflectivity data. This is not for the entire population of signs in North Carolina, only for a sample of signs that would be measured by the new employee. The research committee noted that they would like for the signs legibility distance method not be used nor for sign inspection services to be contracted out; all of the alternatives meet these objectives.<BR><BR></FONT><FONT face=Verdana size=2>The overall desired outcome of the chosen solution is to ensure all signs in the state of North Carolina possess adequate retroreflectivity at all times. Each alternative has a varied approach to meeting the overall desired outcome of achieving maximum compliance.<BR><BR></FONT><FONT face=Verdana size=2>The conclusions resulted in a recommendation of alternative 4, the combination of alternatives 2 and 3, improving on the current method and implementing a sign inventory management system. Although the most costly, this alternative met the most goals and objectives outlined in this report and by the NCDOT research committee. Alternative 4 continues the current nighttime visual inspection, keeps record of sign inspections and the condition of signs, samples a population of signs with a retroreflectometer, and improves training, along with achieving many other objectives.<BR><BR></FONT><FONT face=Verdana size=2>It is also recommend that the GPS-based inventory method be implemented to create the sign inventory management system. Much of the necessary equipment and software is already owned by NCDOT and, using a team of interns at a low labor rate, this could be done for a considerable amount less than some estimates generated from existing literature. The cost of this inventory method is approximately $228,000 for software, equipment, and data collection. Using this method makes the estimated cost of implementing alternative 4 equal to the lower end of the estimated range at $581,000 - $622,000.<BR><BR></FONT><FONT face=Verdana size=2>A Sign Inventory Management System (SIMS) also serves other purposes such as assisting the state with asset management. A SIMS can also be used as a record-keeping tool that stores record of sign maintenance and inspection. Other benefits of an SIMS include the capability to use laptop computers on nighttime rides to help sign inspectors identify missing signs and running queries to evaluate all signs in a location where there may be a high number of accidents to determine if an additional signs or a higher sheeting grade may help reduce accidents. Also, if the system were to include such details as sheeting material lot numbers, signs in different areas can be traced back to matching lot numbers to identify deficient lots.<BR><BR>The research team also recommends the progress and accuracy of the selected alternative as monitored by the new staff member be compiled and formally submitted to NCDO
Ron KingMustan KadibhaiJanuary 2001 - June 2002
102
Complete
1
2002-017
25
  
8181997Structures & ConstructionBridge DesignThe Behavior of Prestressed High Performance Concrete Bridge Girders for US401 over the Neuse River in Raleigh, NC
High performance concrete (HPC) with higher compressive strength (in the range of 8,000 to 10,000 psi) and increased durability is rapidly gaining acceptance for bridge construction. The goal of this project was to implement and demonstrate the economic benefits of the HPC technology in bridge design and construction in North Carolina, thereby providing a greater value to the public. Specifically, the project monitored the production of HPC in typical plant and field conditions, confirmed the feasibility of producing HPC bridge girders and decks, and validated the expected behavior of bridge superstructures built with HPC girders and decks.<BR><BR>As of December 1999, 29% of the nation's 585,542 highway bridges have been rated structurally or functionally deficient, according to the Federal Highway Administration <A href="http://www.fhwa.dot.gov////bridge/defbr99.htm">http://www.fhwa.dot.gov////bridge/defbr99.htm</A>;. To replace some of these deficient bridges or to construct new bridges, it has been found that high performance concrete (HPC) can be utilized to great advantage in terms of structural efficiency and durability. However, there is a need for more field data on high performance concrete and on the structural behavior when high performance concrete is used.<BR><BR>In 1997, the Federal Highway Administration (FHWA) initiated a program to demonstrate the application of high performance concrete to bridges throughout the United States. The North Carolina Department of Transportation (NCDOT) participated in that program and chose a bridge on U. S. Highway 401 in Raleigh crossing the Neuse River as the site for demonstration. The original design of the bridge with the conventional concrete called for six lines of girders. By using HPC, it was possible to eliminate one line of girders for the entire length of the bridge, thus achieving significant savings for the initial cost of the bridge.<BR><BR>The objective of this research is to monitor the behavior of four prestressed HPC bridge girders used in this NCDOT demonstration project during their casting and to study the properties of the concrete used in the girders. This report provides details of the testing of the concrete and field instrumentation of the bridge girders. Comparisons are made between the experimental and theoretical results.
This research examined the material properties and behavior of four prestressed HPC girders during casting and initial curing. Based on this research, the following conclusions can be drawn:<BR><BR>In general, the HPC used in this research was of good quality. Casting of a mock-up girder to demonstrate the constructability of the concrete was very helpful. The concrete performed well and met the expected results in compressive strength, modulus of rupture, coefficient of thermal expansion, and creep. <BR>The modulus of elasticity of the concrete was lower than expected, most likely due to higher volume fraction of cement paste in the concrete, heat and air curing of the test specimens, and to a lesser extent the characteristics of the coarse aggregate.<BR><BR>The shrinkage of the concrete as measured by using the standard prisms stored in the laboratory exceeded the expected value by as much as 25 percent. However, the full-sized girder specimens placed in outdoor environment showed only 10 to 20 percent of the expected value. Such major differences reflect the effects of specimen size and the difference in the environmental conditions.<BR><BR>The results of the rapid chloride permeability test were higher than expected. The higher values of permeability are most likely the results of higher cement content of the HPC mix and the use of heat and air cure of the test specimens. Both of these two factors could cause more and larger pore structures of the concrete paste, which would in turn increase the permeability of the concrete.<BR><BR>During concrete curing, the temperature measured by the embedded thermocouples showed that peak temperatures occurring 7 to 8 hours after casting never reached more than 80º C (176º F). Therefore, there was no danger of thermal cracking.<BR><BR>Based on the load cell readings (Tables 3.1 and 3.2), practically there were no changes of the initial prestressing force up to the time of detensioning. Therefore the measurement suggested that there was no loss of prestress due to strand relaxation prior to detensioning.<BR><BR>Upon detensioning, the transfer lengths for the 0.6 in. strand were found to be 28 and 26 inches, respectively, for Type III and Type IV girders. These values are slightly less than the standard design value of 50 times the strand diameter or 30 in. <BR><BR>During detensioning, the embedded gages recorded compressive strains of 20 microstrain on average for the Type III girders and 435 microstrain on average for the Type IV girders at the mid-span. It appeared that the gages in the Type III girders failed to record the full compressive strain during detensioning possibly due to inadequate consolidation of concrete around the embedded gages. The response of the gages in the Type IV girders were consistent with the predicted values of elastic shortening.<BR><BR>The calculated prestress loss due to elastic shortening was 12.0 ksi for the Type III girders and 18.1 ksi for the Type IV girders.<BR><BR>Total prestress loss was 26.0 ksi (12.9%) for the Type III girders and 38.1 ksi (19.1%) for the Type IV girders. Elastic shortening and creep were the major contributors to the total loss. The loss due to shrinkage was almost insignificant, since the shrinkage strain measured from the full-sized girder specimens was much less than normally expected.<BR><BR>The predicted camber compared closely with the measured camber. The close prediction was possible because the use of load cells at the anchoring end of the prestressing bed provided a more accurate value of the prestressing force at transfer than the normally assumed prestressing force based on estimated loss of prestress. <BR><BR>Prefabricating the instrumentation assemblies in the laboratory was very beneficial. The prefabricated assemblies eased the transportation to the job site, improved the field installation process, and provided excellent protection for the gages and lead wires. <BR><BR>The use of an embedded vibrating wire gage
Greg PerfettiMrinmay "Moy" BiswasAugust 1998 - July 2001
102
Complete
1
2002-003
26
  
101172002Structures & ConstructionBridge DesignBehavior of A New High Performance Concrete Bridge on US 401 Over Neuse River in Wake County
The objective of this research project is to investigate the performance of a full-scale High Performance Concrete (HPC) bridge. <BR><BR>In October, 1996, FHWA entered into a cooperative agreement with NCDOT through which funding was provided for a joint project between NCDOT and North Carolina State University to instrument the HPC bridge on US 401 and monitor its behavior. The project included the following four primary tasks:<BR><BR>Specification of expected properties and associated quality control procedures for HPC concrete produced in typical plant and field conditions, including testing of specimens taken from "full scale" batches. Requirements regarding production and quality control of HPC materials were included in the special provisions for the project. <BR><BR>Internal and external instrumentation of four girders at the plant, and monitoring of temperature and behavior of the girders at the plant. Work included evaluation of transfer lengths of strands at both ends of at least two girders. <BR><BR>External instrumentation of the same four girders after erection at the site, as well as instrumentation of cast-in-place connections between girders. Following instrumentation, performance of the bridge was to be assessed by monitoring short-term behavior through the period immediately following opening of the bridge to traffic. <BR><BR>Long-term evaluation of the structure. <BR><BR>This project was begun as Research Project 1997-08 "The Implementation of HPC in a Set of Dual Four Span Bridges on US 401 in Wake County".<BR><BR>By using HPC, designers can take advantage of not only its structural efficiency but also its enhanced durability. The investigation will focus on the following goal: validating analytical models assumed during design, with a specific emphasis on girder stiffness and deflection calculations, creep and shrinkage effects, and thermal effects.<BR><BR>In order to accomplish these objectives, it is proposed to conduct a live load test on the fully instrumented bridge after it is completed, but prior to its opening to traffic and to follow this with short and long term monitoring for thermal and traffic load effects. Additionally, after the bridge is opened for a full year, a second live load test is proposed to assess if there is any significant change in performance.
Greg PerfettiMrinmay "Moy" BiswasAugust 2001 - June 2003
102
Complete
1
2002-003
27
  
12121998Pavement & MaintenancePavement StrengthDevelopment of a Reliable Methodology to Determine In-Situ Pavement Strength of General Aviation Airport Pavements
Existing airport pavement evaluation and design methodologies are primarily oriented toward larger air carrier size aircraft, and do not adequately address the requirement at General Aviation (GA) airports. Although GA pavements generally serve light aircraft, most airports need to accommodate heavier corporate or military aircraft on an occasional or periodic basis. Existing GA design method cannot handle mixed traffic, or overload operations. <BR><BR>To address these shortcomings and to augment its formal strength rating program, North Carolina Department of Aviation (NCDOA) conducted a two year study during 1997 ¿ 1999 to develop standardized procedures for nondestructive testing (NDT) and evaluation of GA airport pavements and analytical software on layered elastic design theory for evaluating pavement strength and ¿overload operations. <BR><BR>This study focused on flexible pavements and consisted of the following four primary elements: <BR><BR>Field Testing ¿ Nondestructive and conventional tests were performed on one runway at each of six GA airports. <BR><BR>Data Analysis ¿ Back-calculated NDT subgrade moduli were correlated with CBR and laboratory resilient modulus data for development of failure algorithms and to allow direct input of back-calculated FWD subgrade modulus into the evaluation procedure. <BR><BR>Subgrade Strain Criteria ¿ The results of a literature search and design of FAA compliant pavements over a broad range of subgrade and traffic inputs formed the basis of a new subgrade strain failure criterion. <BR><BR>Development of Analytical Software ¿ Layered elastic evaluation and design software developed using the FAA/LEDFAA software for air carrier pavement as a model. <BR><BR>The new software, termed LEDGA, incorporates the new subgrade strain criterion and permits multiple airport analysis and evaluation of ¿overloads¿ based on cumulative damage concepts.
Data from FWD testing can be used to estimate the in-situ elastic modulus of subgrade soils (E sub). The back-calculated E sub can be used as an input to characterize subgrade for layered elastic analysis. <BR><BR>The MODULUS program can be used to back-calculate E sub. <BR><BR>E sub and CBR for the test conditions of this project can be related by: E sub = 1000 CBR <BR><BR>FWD tests should generally be performed at 9,000 to 12,000 lbs., provided the range of the response sensors are not exceeded. <BR><BR>Consistent with current FAA criteria, flexible pavement failure was related to vertical strain, ¿ v, in the subgrade. <BR><BR>The revised ¿ v failure criteria was incorporated into the new GA pavement evaluation program. <BR><BR>Consistent with FAA procedures contained in LEDFAA, a cumulative damage concept for traffic was used in the new GA airport pavement evaluation program. <BR><BR>The LEDGA program developed through this study retains many of the familiar LEDFAA features and materials defaults. In addition to subgrade modulus, other program inputs include: <BR><BR>GA aircraft traffic forecast<BR>Overload aircraft conditions<BR>Pavement thickness and composition<BR>Design life
William H. WilliamsMrinmay "Moy" BiswasJune 1997 - June 1999
102
Complete
1
1999-009
28
  
14181998Pavement & MaintenanceAsphalt Mix DesignAn In-Depth Evaluation of Moisture Sensitivity of Asphalt Mixtures
The main objective of this research was to evaluate current test methods employed to determine moisture sensitivity as well as provide research into new methods for measuring moisture susceptibility. Currently AASHTO T-283 is used almost exclusively to determine moisture susceptibility of an asphalt mix. However, within the AASHTO T-283 procedure a range of values are allowed for important test variables. Specifically tge variables are sample air voids and degree of saturation prior to conditioning. It is important to understand the effect of these variables have on test results.<BR><BR>An alternate to measuring indirect tensile strength is a test that evaluates a mixture's fundamental material properties. An objective of this research was to provide a method for evaluating a mixture's moisture sensitivity that is simple to perform and provides information on the mixture's cohesion and friction angle. A relatively simple test is proposed that measures cohesion and friction angle for asphalt mixtures. In addition, it is desired to incorporate the SST as a tool in moisture sensitivity evaluation. A standard mix analysis test was performed to determine if it was capable of detecting moisture susceptible mixtures.
William H. WilliamsMustan KadibhaiApril 1999 - June 2001
102
Complete
1
2002-102
29
  
161011999Structures & ConstructionConcreteFatigue Performance of Large-Sized Long-Span Prestressed Concrete Girders Impaired by Transverse Cracks
Two full-size AASHTO prestressed concrete girders, one Type III and one Type V, were tested for fatigue resistance. Both girders were impaired by transverse cracks in their top flanges near the midspan and the cracks extended well into the web of each girder. Each girder was subjected to one million cycles of service load and 2,500 cycles of intermittent overload as if the girder were made composite with a cast-in-place bridge deck. The overload was equivalent to 75% of the ultimate capacity of the composite girder. Prior to the fatigue test, each girder was tested beyond its cracking load to create flexural cracks in its tension flange. After the fatigue loadings, the girders were tested to failure to determine their ultimate load capacities.<BR><BR>Analytical studies were also conducted to model the behavior of the girders by using two separate computer programs, one called Cracked Beam and the other Response 2000. The former was developed by using Microsoft Excel and the latter was acquired from the University of Toronto in Canada.<BR><BR>The test results demonstrated that the fatigue loadings had virtually no effect on the girder behavior. The girders showed no degradation in stiffness or strength after 1,000,000 cycles of fatigue loading. Both girders showed considerable ductility, and their ultimate loads and maximum deflections exceeded predicted values
Based on the results of the studies, the following are the findings and conclusions:<BR><BR>For the AASHTO Type III girder, there was no loss of stiffness or strength after one million cycles of fatigue service load with a corresponding stress range of 133 MPa (19.5 ksi) in the prestressing strands, plus 2,500 cycles of overload with a stress range of 201 MPa (29.3 ksi) in the strands. None of the prestressing strands showed any signs of fatigue or failure. The ultimate load obtained from test exceeded the predicted values by the two computer programs by as much as 10%. Also, the ductility of the girder was not affected by the fatigue loadings since the girder deflected 131.8 mm (5.19 in.) at failure which exceeded the prediction of 112.5 mm (4.43 in.) by 17%<BR><BR>For the AASHTO Type V girder, its response to fatigue loadings was quite similar to that of the Type III girder. After completing one million cycles of fatigue service load with a stress range of 96.5 MPa (14 ksi) in the prestressing strands, plus 2,500 cycles of overload causing a stress change of 269 MPa (39 ksi) in the strands, the pre-cracked girder showed no signs of strength or stiffness degradation. The prestressing strands showed no signs of fatigue or failure. The ultimate load obtained from the test exceeded the predicted values by as much as 23%. The ductility of the girder was not affected by the fatigue loadings. Both the actual and predicted deflections of the girder reached nearly 140 mm (5.5 in.).<BR><BR>For both girders, cracking and permanent deflection progressively increased with each segment of 500 cycles of overloading.<BR><BR>Based on the initial cracking load, it was possible to compute the amount of prestress loss, the modulus of elasticity of concrete, and the flexural modulus of concrete, with fairly good accuracy.<BR><BR>The analytical results from both computer programs were sufficiently accurate in predicting the structural performance of the girders. In general, the predictions made by Cracked Beam were closer to the experimental results than the predictions made by Response 2000 and Cracked Beam is simpler to apply. If desired, the NCDOT Structures Unit could implement Cracked Beam program as a tool to evaluate the performance of cracked girders in the future.<BR><BR>The research demonstrated that the current AASHTO LRFD limit of 124 Mpa (18 ksi) on stress range in strands subjected to fatigue loading is a suitable design criterion. <BR><BR>The primary objective of this research was to evaluate the fatigue performance of large-sized long-span prestressed concrete AASHTO bridge girders which had been impaired with transverse cracks near the midspan. Based on the results of this investigation, it is recommended that the current AASHTO LRFD criterion on fatigue loading be applied to evaluate such cracked girders. If a cracked girder is analyzed as a fully cracked section under fatigue service loading and the stress range in the prestressing strand does not exceed 124 MPa (18 ksi), then the girder can be accepted for service.
Greg PerfettiMrinmay "Moy" BiswasJuly 1998 - June 2000
102
Complete
1
2002-024
30
  
181021999Pavement & MaintenanceConcrete PavementsDetermination of Subgrade Strength Under Intact Portland Cement Concrete Slabs for Rubblization Projects
<P><FONT face=Verdana size=2>Rubblization is an effective rehabilitation method for deteriorated Portland Cement Concrete (PCC) pavements due to its low initial cost, minimum traffic disruption, and ability to minimize reflective cracking in asphalt overlays. However, the loss of strength in PCC slabs due to rubblization creates the demand for a subgrade that is strong enough to handle traffic after rubblization. AASHTO recommends Falling Weight Deflectometer (FWD) testing of PCC pavements before rubblization to ascertain the subgrade strength after rubblization.<BR><BR>However, the existing deflection analysis methods do not adequately handle the change in stress states in the subgrade before and after rubblization, and therefore result in erroneous prediction of subgrade strength.</FONT></P><br><P><FONT face=Verdana size=2>The primary objective of this study is to develop an analysis method that allows the realistic estimation of subgrade strength after rubblization from deflection measurements on intact PCC slabs before rubblization. As a forward model, stress/strain dependent nonlinear subgrade models were incorporated into a finite element analysis. ABAQUS and NCPAVE, a finite element code developed at North Carolina State University, were used in the analysis. Multi-load FWD testing was conducted in the field to generate varying stress states in the subgrade under intact PCC pavements. Based on the synthetic database generated from the finite element analyses, a number of relationships were developed using regression and Artificial Neural Network (ANN) approaches to predict the coefficients in the nonlinear subgrade model from multi-load FWD deflections. The verification study was performed on the resulting algorithms using limited field data derived from US 29 in Guilford County and I-85 in Rowan County. The research suggests that the stress-based regression approach, which determines the nonlinear coefficients by regressing between the subgrade moduli and stresses predicted at several radial distances from the FWD load from multi-load deflections, is the most promising method of analysis. The research team strongly recommends the further verification of this procedure using additional field data before the implementation.</FONT></P>
<P><FONT face=Verdana size=2>In this research, the nonlinear subgrade condition was investigated using multi-level FWD loads on intact PCC slabs. Both the stress and strain-based models were studied to represent the subgrade nonlinearity. The nonlinear coefficients in these models were determined either by presenting them directly from ANNs or by running regression analysis between stresses (or strains) and subgrade moduli predicted from surface deflections. The performance of these approaches was evaluated using the data from I-85. The following conclusions may be drawn from this investigation: </FONT><BR></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>The nonlinearity of subgrade is important to estimate subgrade responses, such as stresses and strains, under multi-level FWD loads. The study shows that deviator stresses calculated from the nonlinear analysis are generally larger than those from the linear analysis. That is, the linear analysis could underestimate the subgrade response.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>In general, stresses and strains in subgrade are easier to be predicted from deflection using ANNs than nonlinear material properties. Additionally, the investigation shows that in -situ FWD tests are better than destructive coring and lab test approaches.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Results from this study confirm that the highest FWD load on a thick and/or strong layer cannot cause nonlinear behavior in subgrade. When the predicted stress in subgrade is less than 0.5 psi, coring followed by DCP testing is recommended for subgrade stiffness evaluation.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Based on very limited field data from I-85, the stress-based regression approach seems to be most promising.</FONT> </FONT></LI></OL><br><P><FONT face=Verdana size=2>This research has resulted in a significant amount of information regarding the subgrade nonlinearity under multi-level FWD loads. Several procedures of predicting subgrade nonlinearity under intact PCC slabs have been developed in this research using the dynamic and nonlinear synthetic database. However, the complexity involved in the nonlinear analysis requires the verification of these procedures using field data. Only very limited data were available for this purpose during the research. It is strongly recommended to verify these procedures using additional field data in the future. The additional verification effort will require: (1) deflections measured on PCC slabs using 9, 12, and 15 kip loads; (2) deflections measured on bare subgrade using 3, 5, and 7 kip loads; (3) DCP readings; and (4) laboratory resilient moduli values of soil samples. With this additional work, a reliable backcalculation program for PCC pavement can be developed that will aid not only rubblization decisions but also the overlay thickness design after rubblization.</FONT></P>
Shin WuMustan KadibhaiJuly 1998 - June 2000
102
Complete
1
2002-010
31
  
201031999Pavement MaterialsDelamination and Shoving of Asphalt Concrete Layers Containing Baghouse Fines
<P><FONT face=Verdana size=2>This study investigated the cause(s) of the excessive delamination and shoving distresses observed in NCDOT Division 13. Two possible causes of these distresses were identified to be: 1) the intermittent purging of the baghouse fines in in-situ asphalt mixtures, and 2) improper selection and/or application of the tack coat, i.e. the use of CRS-2 emulsion versus the PG64- 22 asphalt binder. <BR><BR></FONT><FONT face=Verdana size=2>Laboratory performance test results on field cores and asphalt mixtures showed that baghouse fines had a stiffening effect on mixtures and these mixtures were more resistant to rutting. However, mixtures containing baghouse fines were found to be moisture sensitive with tensile stress ratios below that specified by NCDOT. The performance test results for the evaluation of the bond strength of the in-situ cores, showed that the PG64-22 binder used as tack coat provided a better interfacial bonding compared to the CRS-2 emulsion. <BR><BR></FONT><FONT face=Verdana size=2>Results of this investigation suggest that the delamination and shoving distresses in NCDOT Division 13 could be attributed to the combined effect of intermittent purging of baghouse fines in asphalt mixtures and the use of CRS-2 emulsion as tack coat. Due to intermittent purging of baghouse fines, some in-situ mixtures may contain significantly higher proportion of baghouse fines compared to regular fines. Although the NCDOT JMF requires use of an anti-strip additive, the dosage does not appear to be sufficient to offset the increased moisture damage leading to in-situ mixture deterioration and, consequently, loss of strength and stability. Once the moisture damaged mixture is susceptible to shoving under traffic loading, the CRS-2 emulsion may not provide the tacking strength necessary for the surface layer to remain bonded to the lower layer, hence, leading to delamination.</FONT></P>
Mustan KadibhaiJune 1998 - December 1999
102
Complete
1
2002-011
32
  
221041999Pavement ConstructionDynamic Cone Penetrometer Criteria for Evaluation of Subgrade and Aggregate Base Courses
<P><FONT face=Verdana size=2>This report summarizes the findings of one-year research study sponsored by the North Carolina Department of Transportation on the use of the DCP to develop a pavement distress evaluation model. Work included laboratory and field testing programs as well as modeling effort. In this report, a method was proposed by which the DCP PR data were utilized to evaluate pavement distress state. Such evaluation is needed on regular basis in order to categorize the implementation of rehabilitation measures. The principle idea was to use the DCP data to discern the integrity of the subase and ABC layers. Accordingly, if the structural integrity of subgrade and ABC layers is found to be adequate, maintenance measures can include simply resurfacing or treating the surface layer. However, in situations where the structural integrity of the ABC, the subgrade, or both, is found inadequate, extensive stabilization and soil improvement measures maybe needed and resurfacing alone will not be sufficient. <BR><BR><BR>The laboratory work on the subgrade materials was performed on three residual soil types taken from test sites in Davidson County, North Carolina. Testing included compaction of soil specimens in a 150 mm (6 in) mold, performing the CBR test on the prepared specimens, and then penetrating the specimens with the DCP probe. In parallel, the laboratory testing on the ABC materials included the preparation of thirty-two CBR specimens using material from two different sources. The field testing included work at seven sites with three CBR tests, seven DCP penetrations, three nuclear gauge measurements, three FWD tests and one bulk sample extraction conducted at each site. A second phase of field testing at three sites was also performed. Modeling work included development of correlation between the PR and CBR of subgrade soils, PR and CBR of the ABC material, and PR and compaction unit weight and moisture content of the subgrade soils. In addition, the coupled PR-subgrade and PR- ABC data were used to develop a pavement distress level that provided an indication of the test sites pavement's serviceability level.</FONT></P>
Mustan KadibhaiJuly 1998-June 1999
102
Complete
1
2002-013
33
  
222061999Sampling and Testing of Stormwater Runoff from North Carolina Highways
<P><FONT face=Verdana size=2>This project presents research findings pertaining to the implementation of a comprehensive monitoring program for characterization of North Carolina highway runoff. Ten monitoring sites were included in the study. The sites were distributed in the Piedmont region (6), the mountain region (2), and the coastal region (2). Contributing drainage areas ranged from 0.15 to 13.26 acres. Roadway imperviousness ranged from 22% to 100%; traffic volumes, measured in vehicles a day (both directions) ranged from 9,400 to 78,800. Rainfall-runoff data and composite storm water samples were obtained from 237 storm events. The effectiveness of vegetative best-management practices (BMPs) was assessed by comparing pollutant exports from three groups of paired monitoring sites. A database was established for estimation of seasonal and annual pollutant loads and event-mean-concentrations (EMCs). The study was part of NCDOT¿s effort to comply with National Pollution Discharge Elimination System (NPDES) requirements. </FONT></P>
G. Dennis PipkinOctober 1998 - June 2001
102
Complete
1
2001-002
34
  
241071999Wetlands MitigationFunctional Assessment of the Effects of Highway Construction on Coastal North Carolina Wetlands: Comparison of Effects Before and After Construction: Phase II (Construction)
<P><FONT face=Verdana size=2>A major challenge in environmental monitoring is differentiating of true impacts from changes due to natural variation or cycles in ecosystem function. In our study the use of the BACI sampling design has allowed for discrimination of construction impact from natural variation. Impacts have been detected in salinity, sediment accretion, D.O., phosphorus concentration, macrophyte community composition, algal productivity as well as macroinvertebrates and fish. These changes are likely the result of construction of the highway bypass of Jacksonville , NC . It is impossible to say whether these impacts will prove to be short-term or persist beyond the completion of the highway since data collection after construction was discontinued due to a lack of funding. It appears the impacts resulting from construction phase increased rates of runoff from the watershed due to road clearing, impeded fluxes of water from floods and importantly tides due to the presence of temporary culverts at the site. Changes in soil surface elevation due to sediment displacement during road fill placement, and increased sediment flux from road fill and clearing also occurred. These impacts should be temporary, and the system may return to its normal state after several growing seasons, provided sediment and nutrient changes do not remain altered. Of concern, however, is the impact of reduced salinity on the long-term biota of Wilson Creek . Unfortunately, the study has not been continued so it is impossible at this stage to assess the recovery of the site and determine if the biota have returned to conditions near the reference conditions. Fortunately, the design of the study will allow for a follow up study to assess recovery. </FONT></P>
G. Dennis PipkinApril 1999 - December 2001
102
Complete
1
2002-16
35
  
261081999EnvironmentWater Quality and Pollutant DischargeEmissions Reduction Through Better Traffic Management: An Empirical Evaluation Based Upon On-Road Measurements
<P><FONT face=Verdana size=2>In this study novel methods have been used for evaluating strategies aimed at preventing motor vehicle air pollutant emissions through better traffic management. Actual on-road emissions measurements were utilized in contrast to the laboratory-based dynamometer tests employed in many current projects. The primary objectives of this research were to:</FONT><BR><BR>1.&nbsp; <FONT size=2><FONT face=Verdana>Assemble, evaluate, and validate a new low-cost on-board emissions measurement (OEM-2100TM) system;</FONT> </FONT><FONT size=2><FONT face=Verdana><BR><BR>2.&nbsp; Investigate factors that affect the level and variability of on-road emissions using rigorous statistical methods;</FONT> <BR><BR>3.&nbsp; </FONT><FONT size=2><FONT face=Verdana>Devise methods for designing and conducting experiments that realistically evaluate vehicle-based pollution prevention strategies.</FONT> <BR><BR></FONT><FONT face=Verdana size=2>Objective (1) was satisfied via the procurement of two OEM-2100TM portable on-road tailpipe emissions measurement systems. Objective (2) was satisfied by developing a data collection protocol, collecting on-road emissions data, and analyzing the data using graphical, statistical, and theoretical approaches. Objective (3) was satisfied by designing and conducting a real-world emissions measurement study before and after the implementation of changes to signal timing and coordination on two separate study corridors. <BR><BR></FONT><FONT face=Verdana size=2>The project proceeded in two major phases. The first, or pilot, phase, involved preliminary deployment of the OEM-2100TM with specific vehicle, driver, route, and scheduling combinations for purposes of developing data collection and reduction protocols and to develop a preliminary database for use in identifying potentially important factors influencing emissions. Based upon the lessons learned in the pilot phase, an experimental design was developed for the second, or evaluation, phase of the project. The evaluation phase focused on detailed evaluation of the change in vehicle movement and emissions associated with a change in signal timing and coordination on two corridors, each approximately two miles long.<BR><BR></FONT><FONT face=Verdana size=2>The specific pollution prevention strategy evaluated in this project was modification of signal timing and coordination as a means to improve traffic flow. The pollutants studied include carbon monoxide (CO), nitric oxide (NO), and hydrocarbons (HC). A hypothesis that motivated this project is that vehicle emissions are sensitive to micro-scale events that occur during a trip or along a specific corridor. Such events, such as accelerations at intersections, may cause relatively high emission rates. Therefore, efforts to smooth traffic flow by improving signal timing and coordination may lead to a reduction in the number of accelerations and, hence, lead to reductions in emissions.<BR><BR></FONT><FONT face=Verdana size=2>Portable instruments were used for measuring carbon monoxide (CO), nitric oxide (NO), and hydrocarbon (HC) emissions and vehicle activity (e.g., vehicle speed, engine parameters) on a second-by-second basis. Data collection, quality assurance, reduction, and analysis protocols were developed. Field data collection occurred in a pilot and an evaluation phase. In total, over 1,200 one-way trips were made with more than 20 vehicles, 4,000 vehicle-miles traveled, 160 hours of data, and 10 drivers. The pilot study was used to identify key factors influencing on-road emissions and as input to the design of the evaluation study. In the evaluation study, data were collected intensively with a small number of vehicles on two corridors before and after signal timing and coordination changes were implemented. </FONT></P>
Mike T. StanleyG. Dennis PipkinApril 1999 - June 2001
102
Complete
1
2002-015
36
  
281091999EnvironmentMiscellaneousA Two Stage Evaluation of NCDOT Stream Mitigation Practices: Stage 1-Synthesis of Current Stream Mitigation Practices; Stage 2-Development of Criteria of Effective Mitigation
<P><FONT face=Verdana size=2>Stream restoration and mitigation is a complex process that involves recognizing natural and human induced disturbances that degrade the form and function of stream and riparian ecosystems or prevent its recovery to a sustainable condition. Restoration includes a broad range of activities designed to enable stream corridors to recover dynamic equilibrium and function to maintain channel dimension, pattern, and profile so that over time the stream channel does not degrade or aggrade. <B>The Stream Corridor Restoration: Principles, Processes, and Practices </B>manual published by the Federal Interagency Stream Restoration Working Group in 1998 identifies three levels of stream improvement: 1) restoration, 2) rehabilitation, and 3) reclamation. <B>Restoration</B> is defined as the reestablishment of the structure and function of ecosystems. Ecological restoration is the process of returning an ecosystem as closely as possible to predisturbance conditions and functions. Ecosystems are dynamic and therefore it is not possible to recreate a system exactly. The restoration process reestablishes the general structure, function, and dynamic but self-sustaining behavior of the ecosystem. Rehabilitation is defined as a procedure for making the land useful again after a disturbance. It involves the recovery of ecosystem functions and processes in a degraded habitat. <B>Rehabilitation</B> does not reestablish the predisturbance condition but does establish geological and hydrologically stable landscapes that support biological diversity. <B>Reclamation</B> is defined as a series of activities intended to change the function of an ecosystem, such as changing wetland to farmlands.<BR><BR></FONT><FONT face=Verdana size=2>For this project, stream restoration is defined as returning a degraded stream ecosystem to the highest level of stream potential available for the surrounding landform. This includes reestablishment of stream channel that maintains its dimensions, pattern and profile such that over time it does not aggrade or degrade. This definition also implies that the restoration will provide the highest level of aquatic habitat and biological diversity possible.<BR><BR></FONT><FONT face="Verdana, Arial, Helvetica, sans-serif" size=2><FONT face=Verdana size=2>This project included a thorough review of scientific literature related to stream restoration techniques and practices in addition to development of a design handbook. Literature review topics included fluvial processes, bioengineering, natural channel design, habitat improvement structures, stream stability, and sediment transport. An annotated bibliography of the relevant stream restoration literature was posted to the NCSU Water Quality Group Web Site at:<BR><BR><A href="http://www.bae.ncsu.edu/programs/extension/wqg/">http://www.bae.ncsu.edu/programs/extension/wqg/</A>&nbsp;<BR><BR></P><br><P><FONT face=Verdana size=2>The document "Stream Restoration: A Natural Channel Design Handbook" was prepared and distributed to 35 NCDOT participants in a 4-day workshop held in Raleigh, NC January 22-26, 2001. The Handbook includes detailed descriptions of successful current and proven stream restoration practices integrated into a usable and reliable cost-effective process for NCDOT. Chapter 11 in the Handbook is a comprehensive process to support evaluation of successful stream restoration.</FONT></FONT><BR></FONT></P>
<P><FONT face=Verdana size=2>Stream restoration research is needed in many areas to evaluate the techniques currently being applied for natural channel design. This research need can be conducted in the context of monitoring and evaluation as well as in specific channel-oriented process applicable to stream restoration. Among the published literature attempts to address these gaps, at present, most only succeed in suggesting what needs to be done for restoration rather than actually doing what is suggested. On the other end of the spectrum, restoration specialists involved specifically in stream restoration are not publishing their findings, either due to time, monetary constraints or disinterest. The disparity between these two groups may simply be the disconnection between science and management; however, the need for cooperation still exists. A short list of future research needs include examination of the following:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Comparison between holistic and non-holistic approaches to restoration</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Designing for the bankfull channel</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Testing regional curves</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Region specific restoration in terms of past and present land use change</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>The significance of channel change history to restoration design (Does it really make a difference?)</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Specific limitations of classification systems in restoration design (Are there any, and if so, what are they?)</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Multi-goal restoration: Consideration for combined physical and biological function</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Success rates of stream restoration: What works where?</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Failure rates of stream restoration: What does not work where?</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Spatial and Temporal effects of in-stream structures.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2><B>Implementation &amp; Technology Transfer Plan</B></FONT></P><br><P><FONT face=Verdana size=2>Thirty-five NCDOT staff members participated in a four-day workshop on stream restoration design January 23-26, 2001, at the NC State University McKimmon Center. Instructors were Greg Jennings, PhD, PE, Barbara Doll, PE, Dani Wise-Frederick, and Karen Hall. All instructors are faculty members of NCSU's Stream Restoration Institute, an interdisciplinary group focused on education and applied research to promote natural channel design approaches to restoring and enhancing streams and rivers. Participants included several Natural Systems staff members, the Division Environmental Officers from all 14 divisions, and staff from Roadside Environmental and Hydraulics.</FONT></P><br><P><FONT face=Verdana size=2>Workshop topics included the Rosgen stream classification system, stream condition assessment, causes of stream instability, restoration options, case studies of North Carolina projects, reference reach surveys, and natural channel design processes. In addition to daily classroom sessions, Workshop participants visited local streams each day to collect data and observe construction of two active restoration projects in the Raleigh area. Participants learned by example about stream channel geometry measurements, design and installation of in-stream boulder and log structures, streambank stabilization techniques, and riparian vegetation management. All of these project components are essential to successfully restore the natural functions of impaired stream systems. </FONT></P><br><P><FONT face=Verdana size=2>The project case studies were valuable for helping staff members understand what is involved in project planning, design, construction management, and monitoring. The
David RobinsonG. Dennis PipkinAugust 1999 - June 2000
102
Complete
1
2002-015
37
  
301101999EnvironmentWetlands MitigationAn Evaluation of the Effectiveness of Existing North Carolina Department of Transportation Wetland Mitigation Sites
<P><FONT face=Verdana size=2>In this study, 49 NCDOT wetland compensatory mitigation sites and 11 reference sites were evaluated on-site in 1999. Seventeen of the larger sites consisted of more than one type of mitigation (restoration, creation and/or preservation). In total, 71 mitigation parcels (approx. 3,000 acres) were evaluated to assess the likelihood that mitigation sites would achieve some level of structure and functioning similar to natural, self-sustaining wetland ecosystems and to provide recommendations for improvements. Ecological success was related to whether or not natural geomorphology had been successfully restored. Sites from which fill was removed were generally successful. Sites in which water impediment structures were constructed showed mixed results for vegetation survival, presumably because it was difficult to determine how wet to make a site. Wetland creations were generally unsuccessful because most all involved excavating soil to reach the underlying saturated zone, thus inhibiting growth of vegetation on sub-soils. Predictions of success were difficult due to the immaturity of sites, but it appeared that many created wetlands would not likely resemble historic, natural ecosystems. Of the 71 compensatory mitigations examined, 26 were judged to be ecologically successful, 19 were preservation sites (automatically judged to be successful), 9 were judged to be unsuccessful, 10 lacked sufficient data (mostly hydrologic data) for judging success, 4 sites were too young to predict the outcome for vegetation survival, and 3 were undergoing construction at the time of our site visit. Alteration of and failure to restore natural geomorphology in compensatory mitigation sites was the major factor associated with the lack of mitigation success, regardless of whether success was defined by permit success criteria or by ecological success. More use of information from reference sites could improve outcomes. Compensatory wetland mitigation involving restoration and creation appears to have gravitated toward relatively narrow sets of conditions for hydrology and vegetation, with little room for flexibility. In contrast, no standards are being used for soil condition. Current success criteria and standards should undergo critical examination to see if they are consistent with no-net-loss wetland policies, and if alternative measures should to be taken.The Phase 2 component of this research examines five of the compensatory mitigation sites to provide a more in-depth analysis. The objective of the two reports is to help NCDOT and wetland regulatory agencies develop a framework to improve NCDOT's compensatory mitigation, to enhance communication between NCDOT and regulatory agencies, and to benefit wetland restoration overall. We encountered problems with various definitions (restoration, preservation, enhancement, etc.) that are not compatible with current scientific understanding of ecosystem functioning. This has led to avoiding the potential for improving the condition of severely altered wetlands because they meet the jurisdictional definition in spite of a highly degraded condition. Elsewhere, socioeconomic limitations may prevent complete restoration. In such cases, partial restorations may be better than none at all. For example, preservation through purchase or conservation easements of headwater streams and their buffers in a partially degraded condition would provide opportunities for improving water quality. Undue reliance on criteria for hydrology over criteria for soil, in extreme cases, has led to soil excavation that reduced survivorship of planted seedlings and lowered recruitment capacity. In general, reference sites have been little utilized to design restorations and to gauge success. Depending on initial conditions, the restoration of wetland structure and function may take many decades to achieve maturity. Presently, all monitoring stops once permit conditions have been met. Institutional mem
<FONT face=Verdana size=2><br><UL><br><LI><FONT face="Verdana, Arial" size=2>Success criteria for vegetation seemed to require survival of some minimum density after a prescribe period of time for the entire site. If plant survival data are averaged (pooled) across plots within a given site, valuable information on variability may be lost, and may prevent expressing projects as having partial successes or failures. Similarly, when data on intra-site variation are lacking, contingency measures cannot be effectively applied to pertinent portions of a project. </LI></UL></FONT><FONT size=2><br><UL></FONT><FONT face="Verdana, Arial" size=2><br><LI>Vegetation monitoring plots were often not stratified by cover-type or geomorphic location. Therefore, one could not tell whether a particular planting mix was appropriate for the geomorphic location of the planting. </LI></UL></FONT><FONT size=2><br><UL></FONT><FONT face="Verdana, Arial" size=2><br><LI>Vegetation monitoring plots did not appear to be randomly placed and sometimes did not seem to represent the geomorphic variability within sites. We suggest that a written protocol be established for determining the location and numbers of plots needed to provide an unbiased estimate of survival. </LI></UL></FONT><FONT size=2><br><UL></FONT><FONT face="Verdana, Arial" size=2><br><LI>Although permanent plots provide useful information on the survival of planted species and degree of colonization by "volunteer" species, we suggest that they not be used as the sole source of information on survival, particularly since there may be a problem with plots representing variability within sites (see 3 above). If plots are not chosen randomly or according to some established protocol, one could legitimately question whether plots were placed where they were judged to be least likely to fail. An <EM>a priori </EM>procedure for the placement of plots would avoid any appearance of bias. </LI></UL></FONT><FONT size=2><br><UL></FONT><FONT face="Verdana, Arial" size=2><br><LI>We couldn't find any rationale for the various tree survival success criteria required by the Corps of Engineers. (One of the most commonly used criterion (Appendix B) was 320 trees/acre surviving after 3 years, although this protocol seems to have been revised to 320 stems/acre surviving for 3 years with no more than a 10% reduction per year for a subsequent 2 years.) We realize that specific density criteria was guidance established by the U.S. Army Corps of Engineers and negotiated with the agencies, but the rationale (perhaps provided as a citation) for requiring a given density should be provided in the monitoring reports (assuming the Corps used published information to establish its guidelines). In addition, because mortality of tree seedlings is somewhat inversely related to height, survival criteria for forest restoration would be more useful if based on survival to the sapling stage (perhaps to &gt; 1.5 or 2.0 m in height), rather than length of survival. Otherwise, planted trees might survive for 3-5 years, but not grow larger, a condition that would not be sustainable over the long-term. Also, some success criteria required that 6 hardwood mast species survive with no more than 20% survival attributed to any one species. Some requirements prohibit more than 10% softwood species as well. These criteria require that all six mast species have to range between 15% and 20% of the total density. It is unlikely that any planting regime could succeed under such stringent conditions.</FONT><FONT size=2><FONT face="Times New Roman"> </FONT></LI></UL><br><UL></FONT><FONT face="Verdana, Arial" size=2><br><LI>Monitoring reports did not provide information on plot size. We were further confused by the application among plots of different constants to determine stem density, leading us to assume that plots varied in size. We later learned that these differences were based on survival data which had in turn been based on initial plantin
David SchillerG. Dennis PipkinApril 1999 - June 2001
102
Complete
1
2000-002
38
  
522182001Structures & ConstructionBridge Maintenance and ManagementBridge Management System Update
<P><FONT face="Verdana, Arial, Helvetica, sans-serif" size=2><FONT face=Verdana size=2>The objective of this project was to assist the NCDOT in updating parameters used in analysis of bridge inspection data for purposes of bridge management. Various parameters are used in OPBRIDGE, a bridge manage system decision support program for predicting optimum use of funds budgeted and for predicting performance of the bridges of the State of North Carolina in future years under various level of funding. In particular, the project examined and developed parameters for: </FONT><br><OL><br><LI>Unit costs of replacements; <br><LI>Unit costs for rehabilitation; <br><LI>Maintenance effort as a function of element condition; <br><LI>Deterioration rate for major bridge elements; <br><LI>ADT growth rates for the bridge functional classifications and locations; <br><LI>Bridge-related accident unit costs; and <br><LI>Vehicle operating costs. </LI></OL>In most cases, improvements over the previous parameter values were possible as documented in this report. </FONT>
Neal GalehouseJanuary 2001 - December 2001
102
Complete
1
2005-06
39
  
541052002Coastal Highway Vulnerability
<P><FONT face=Verdana size=2>This research will update and refine the highway vulnerability study prepared by the Principle Investigators for NCDOT in 1991 by making use of more recent topographic data and by improving the methodology to include short term storm events. This update will be based upon the most recent (1998) aerial photographs available of the entire North Carolina coast for the base maps and the determination of long-term erosion rate. In addition, the project will make use of high-resolution digital terrain models that reflect the topographic changes that have occurred in the 1990s. Finally, the revised study will incorporate a statistical method to evaluate the risk of the combination of long-term erosion and storm damage to the NC coastal highway system. This will allow the development of a more comprehensive assessment of the vulnerability of the NC coastal highway system. The project report will provide a guide to NCDOT as to what portions of the coastal highway system will be likely to sustain damage or require mitigation for the next twenty years. </FONT></P>
G. Dennis PipkinJuly 2001 - June 2003
102
Complete
1
2004-04
40
  
561062002Traffic & SafetyTraffic SafetyEvaluating the Effects of Continuous Median Barriers on Freeway Speeds and Emergency Response Service Times
<P><FONT face=Verdana size=2>In 1996, the NCDOT increased the speed limits on interstate highways and full control access facilities to as high as 70 mph. Studies have shown that the increased speed limits result in travel speeds typically a few miles per hour above the posted speed limit. An earlier study conducted by NCDOT shows that increased speed limits also increased speed creep, the gradual increase of travel speeds.</FONT></P><br><P><FONT face=Verdana size=2>In 1998, NCDOT implemented a program to save lives by preventing across median crashes by providing positive barriers on all freeways with median 70 feet or less. The barrier seals off the median with limited openings for maintenance at transitions near bridge piers in the case where cable barrier is installed. The lack of breaks limit the locations where emergency vehicles and law enforcement officers can turn around. The respective agencies claim that the barriers adversely affect their ability to perform their duties.</FONT></P><br><P><FONT face=Verdana><FONT size=2>The results of the project should provide NCDOT with objective measures concerning the effects of continuous median barriers on speeding, speed-related crashes, response and transport times. This allows the department to establish performance-based policies concerning this critical safety issue.<BR></FONT><BR><B><FONT size=2>Objectives:</FONT></B></FONT></P><br><P><FONT face=Verdana size=2>The main objectives of the research project are:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>To determine effects of continuous barriers on vehicle speeds, speed related crashes, response times, and transport times.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>To determine if median crossovers achieve desired results with respect to speed management, response times, and transport times.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>To determine the level of unauthorized use of existing median crossovers.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>To review signage used by neighboring states to mark median crossovers.</FONT> </FONT></LI></UL>
A. D. (Tony) WyattMustan KadibhaiJuly 2001 - June 2003
102
Complete
1
2003-05
41
  
581072002Pavement & MaintenancePavement PerformanceImpact of Price Reductions on the Long Term Pavement Performance of Hot Mix Asphalt Mixes in North Carolina
<P><FONT face=Verdana size=2><FONT color=#000000>Article 105-3 of the North Carolina Department of Transportation (NCDOT) Standard Specifications for Road and Structures </FONT>provides guidance on price adjustments for hot mix asphalt pavements that are not within reasonably close conformity with the specifications but for which the work is to be accepted and remain in place. The primary objective of this research is to refine these price adjustments.</FONT></P><BR><br><P><FONT face=Verdana size=2>The research objective will be accomplished by conducting both field and laboratory analyses of deficient pavements and specification pavements with similar structures and traffic history. The types of deficiency to be addressed in this research include asphalt content and in-situ density. Both fatigue and rutting performance will be evaluated. The field study will include the analysis of condition survey data and available Falling Weight Deflectometer (FWD) data for remaining life prediction. The remaining life prediction algorithm using FWD deflections that will be used in this report was determined by a related <A href="https://apps.ncdot.gov/Projects/Research/ProjectInfo.aspx?ID=361">Research Project 2000-04</A></FONT><FONT face=Verdana size=2><A href="https://apps.ncdot.gov/Projects/Research/ProjectInfo.aspx?ID=361">, "Use of Falling Weight Deflectometer Multi-Load Data for Pavement Strength Estimation."</A> The laboratory study will be performed on cores obtained from eight selected pavements as well as laboratory fabricated specimens of the hot mix asphalt (HMA) mixtures for those pavements. The laboratory <BR>test program will include:</FONT></P><BR><br><OL><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Indirect tension tests for fatigue performance evaluation</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Repeated load triaxial tests for rutting evaluation</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Accelerated pavement tests on laboratory pavement slabs for fatigue and rutting evaluation using the third scale Model Mobile Loading Simulator</FONT> </FONT></LI></OL><BR><br><P><FONT face=Verdana size=2>Both field and laboratory analysis results will be compared to develop prediction models for fatigue and rutting performance of asphalt concrete. Two levels of economic analysis will be performed to determine appropriate pay adjustment factors. The first level uses the ratio of the service lives of specification and deficient HMA mixtures determined from laboratory testing and accelerated pavement testing. The second level involves the life cycle cost analysis of specification and deficient pavements.</FONT></P><BR><br><P><FONT face=Verdana size=2>If necessary, recommendations will be made for revisions to the NCDOT Standard Specifications for Roads and Bridges. In addition, the system comprised of pavement performance prediction models and economic analysis that will be developed from this study will establish a framework on which a future pavement design, rehabilitation design, and performance-related specification (PRS) may be built. </FONT></P>
Judith Corley-LayMustan KadibhaiJuly 2001 - June 2003
102
Complete
1
2005-09
42
  
582082002Pavement & MaintenancePavement PerformanceEffect of Percentage Baghouse Fines on the Amount and Type of Antistripping Agent Required to Control Moisture Sensitivity
<P><FONT face=Verdana size=2>Presently, in North Carolina the baghouse materials used in hot mix asphalt (HMA) are purged intermittently into the AC mixtures rather than being stored in a silo and added to the mixture as mineral filler in a uniform, controlled manner. Previous studies have shown that the volumetric properties of asphalt mixtures are greatly influenced by the source and gradation of the baghouse fines. Due to this reason, several states require contractors to waste baghouse fines. However, there are some environmental concerns with wasting the fines.<BR><BR></FONT><FONT face=Verdana size=2>Recent research (Research Project 1999-03) suggests that baghouse fines with gradation similar to the natural and manufactured fines passing #200 sieve, seem to have a beneficial effect on the stiffness and rutting characteristics of the asphalt mix. However, this recent research did note that these mixes containing baghouse fines were susceptible, and recommended that baghouse fines be metered into the mix to create a uniform percentage throughout the mix.<BR>This project will be a laboratory study of moisture sensitivity of asphalt mixes containing controlled percentages of baghouse fines in the amount of 0, 4, and 8-percent. Antistripping agent(s) selected in consultation with NCDOT will be used to determine their effectiveness in mitigating moisture damage. The study outcome should result in clear recommendations regarding maximum level of baghouse fines, the appropriate type and amount of antistripping agent, and any significant performance issues that are uncovered by the research team.</FONT></P>
Judith Corley-LayMustan KadibhaiJuly 2001 - December 2002
102
Complete
1
2003-04
43
  
601092002PlanningTraffic Surveys, Modeling and ForecastingA Spatial Editing and Validation Process for Short Count Traffic Data
<FONT face=Verdana><EM>"A question often asked in transportation seminars and workshops is how do I validate short-term counts with so little data collected? This project addresses one aspect of that validation process. Exciting and unique not only because of its functionality, it breaks ground on several new fronts as well. First, the analysis will provide a workable technique to validate short-term counts and function as one component within a quality control process. Statistically, a large dataset for a spatial analysis is 250 points. We are attempting to model 37,000 points (permanent count stations). The size and complexity of the data itself poses problems that can't be addressed through standard "packaged" analysis software. This project is a "cutting edge" prototype that can be modified to fit other DOT's validation processes. We are pleased to be participating in this exciting research." <BR></EM>-Susan Cosper<BR><BR><BR><FONT face=Verdana size=2>Within North Carolina, approximately 35,000 traffic counts are recorded annually for the purpose of monitoring the flow of traffic. These counts play a crucial role in allocation of resources for the maintenance, upgrade, and expansion of traffic infrastructure. The need for reliable, edited, and validated traffic count data is well acknowledged by the Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials (AASHTO).<BR><BR></FONT><FONT face=Verdana size=2>This research addresses this need by developing a statistically defensible approach to achieving spatial continuity of traffic counts as part of the editing and validation process. A letter of support from the Director of the Office of Highway Policy Information of FHWA in favor of the research gives further credence to the project.<BR><BR></FONT><FONT face=Verdana size=2>At present, the practice within NCDOT for editing and validation count data is to manually and visually compare current counts to counts from previous years and neighboring stations. If a count is considered unusual, it is often modified to make it more similar to neighboring counts. This process is very slow, is prone to individual subjectivity and bias, encourages excessive adjustments to counts, and does not conform to the FHWA and AASHTO recommendations for incorporating spatial analysis.<BR><BR></FONT><FONT face=Verdana size=2>This research will significantly improve the process by increasing the accuracy of reported counts, by reducing the time delay between data collection and reporting, and by providing easily customized reports of traffic counts to NCDOT departments and customers.</FONT></FONT>
Susan CosperMustan KadibhaiJuly 2001 - July 2003
102
Complete
1
2006-59
44
  
602102002PlanningTraffic Surveys, Modeling and ForecastingGuidelines for NCDOT Project-Level Traffic Forecasting Procedures
<P><FONT face=Verdana size=2>This project documents a methodology and related procedures to accomplish project-level traffic forecasting for NCDOT. While the methodology is general and can guide an engineer or planner through various steps including field visits, local discussions, data collection, analysis and documentation, the procedures provide explicit analytical tools appropriate for the forecasting task. </FONT></P><br><P><FONT face=Verdana size=2>The methodology structures and systematizes the forecasting process using two general methods: (1) the hand method which utilizes spreadsheet procedures to address smaller, rather isolated projects, and (2) TransCAD which can evaluate larger projects that are part of complicated networks. Given Base Year traffic volumes, turning movements, land use and transportation network information, both methods provide estimates of future facility volumes and turning movements assuming alternative development scenarios. The methodology implicitly recognizes uncertainty in the forecasting process regarding development (trip generation) and the importance of truck traffic estimates for design. </FONT></P>
Mustan KadibhaiJuly 2001 - June 2002
102
Complete
1
2002-026
45
  
621112002PlanningPublic & Rural TransportationRegionalizing Public Transportation Services
<P><FONT face=Verdana size=2>The purpose of this research study was to gather information on, and develop preliminary plans for methods to facilitate delivery of public transportation at the regional level in North Carolina. This study identified barriers to the integration of transit systems at the regional level, evaluated best practices from North Carolina and other states, and developed recommendations for programmatic and legislative changes to facilitate the implementation of regional transit systems in both metropolitan and rural areas of the state. <BR><BR>As regions grow in population and geographic area, the demand for transit trips becomes more regional in nature, and transit organizations need to effectively respond to this demand. The creation of a regional transportation agency can offer a number of important benefits:</FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana><STRONG>Benefits to Riders</STRONG>-A primary rationale for creating a regional transportation agency is to provide better service to a region's riders. A multi-county transit agency can more efficiently and effectively accommodate trips that cross county lines, which are common for purposes of medical services, employment, training programs, and special employment programs such as sheltered workshops. An adequately funded regional agency may also be able to hold fares at a more affordable level, and be better able to provide rider benefits such as a centralized travel information center.</FONT> </FONT></LI><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana><STRONG>More Effective Regional Planning</STRONG>-The functions of Metropolitan Transportation Planning Organizations (MPOs) and Rural Transportation Planning Organizations (RPOs) are facilitated when there is a regional transportation agency that can develop a comprehensive regional plan for public transportation operations and investment.</FONT> </FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana><STRONG>Ability to Address Regional Transportation Problems</STRONG>-A regional transportation agency can provide a more effective mechanism for addressing such important regional problems as traffic congestion and air pollution.</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana><STRONG>Adequate Funding for Public Transportation</STRONG>-A regional transportation agency can be created with its own dedicated funding source. This can result in a more coordinated or integrated fare systems, and new service in unserved or underserved areas. Dedicated funding can also insure that the transit system can provide matching funds for state and federal grant opportunities.</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana><STRONG>Transportation and Land Use Planning</STRONG>-An effective regional transportation agency can enable more integrated and balanced land use planning.</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana><STRONG>Operational and Administrative Economies</STRONG>-A regional system can provide many operating benefits such as eliminating duplicate routes from overlapping transit system boundaries, coordinating schedules, and achieving operational economies of scale. Equally important, there are opportunities to realize significant savings and efficiencies by consolidating administrative functions into a single agency. Administrative savings are especially prevalent among small and rural multi-county transit systems. In addition to potential savings in labor costs, there are also opportunities to develop and implement more efficient and effective marketing, fare, and other programs at the regional level. Savings may be reinvested in transit systems to improve the quality of their services.</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY:
<P><FONT face=Verdana size=2>The recommendations presented in this report are divided into those that affect programmatic decisions, legislative decisions, and supplemental steps to implementation as follows:</FONT></P><BR><br><P><FONT size=2><FONT face=Verdana><B>Programmatic Recommendations<BR></B><I>Organizational/Institutional</I></FONT></FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Regional Consultants</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Uniform Human Service Agency Procedures</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Coordination and Consolidation of CTIPs</FONT></FONT></LI></OL><br><P><FONT face=Verdana size=2><I>Funding</I></FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Transitional Funding</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Funding Incentives</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Effective Use of Large Urban, Small Urban, and Rural Area Funding</FONT></FONT></LI></OL><br><P><FONT face=Verdana size=2><I>Operations</I></FONT></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Operations Training and Technical Support</FONT></FONT></LI><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Extra-Regional Coordination</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Distributed vs. Centralized Operations</FONT></FONT></LI></OL><br><P><FONT face=Verdana size=2><B>Legislative Recommendations</B></FONT><BR></P><br><P><FONT face=Verdana size=2><I>Changes to Federal and State Legislation and Policies</I></FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Federal Transportation Legislation</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Coordination with Various Human Service Programs</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Regional Transportation Legislation</FONT></FONT></LI></OL><br><P><FONT face=Verdana size=2><I>Organizational/Institutional</I></FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Creation</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Legal Form</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Territorial Jurisdiction</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Immediate vs. Phased Regional Implementation</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Governance</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>County-by-County vs. Region-Wide Approval of RTAs</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Transportation Advisory Board Funding</FONT></FONT></LI></OL><br><P><FONT face=Verdana size=2><I>Funding</I></FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Dedicated Funding</FONT></FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Funding Equity</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Dedicated Funding</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Revenue Recovery Ratio Requirement</FONT><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>State Public Transportation Funding Appropriation: Administration</FONT></FONT></LI></OL><br><P><FONT face=Verdana size=2><B>Recommendations for Next Steps</B></FONT></P><BR><br><P><FONT face=Verdana size=2>
Charles GloverG. Dennis PipkinJuly 2001 - June 2002
102
Complete
1
2002-025
46
  
641122002Structures & ConstructionBridge Maintenance and ManagementEvaluation of Bridge Analysis vis-à-vis Performance
<P><FONT face=Verdana size=2>Our aging infrastructure components are in need of replacement or significant upgrade. Increased traffic, heavier load requirements and corrosion-related deficiencies all contribute to the critical assessment of the bridge inventory. The regular analyses and inspections often result in postings and/or traffic limitations for bridges. It is believed, however, that the current rating process my underestimate the true performance of some of these bridges, causing unwarranted posting or denial of permits associated with these structures. Clearly, there exists a need to re-evaluate the current analysis procedures and supplement them with additional methods and/or experimental analysis.<BR><BR></FONT><FONT face=Verdana size=2>The objective of the proposed project is to test four bridges in North Carolina, analyze the experimental results, and compare the test data with analytical predictions. Based on this comparison, suggest improvements to the current bridge analysis procedures, and validate them with three additional bridge tests, including one bridge with a glass fiber reinforced polymer (GFRP) bridge deck system. In order to achieve this, seven typical bridges will be selected, instrumented and tested to their service limit (i.e. TRB diagnostic test level). Parallel to these experiments, analysis of these bridges will be conducted using conventional methods currently used by the NCDOT analysis team. Both the AASHTO (1992 and interims) and the North Carolina requirements are considered in the load tests and bridge analyses. The project is being performed in close collaboration with NCDOT engineers and personnel at both divisional and state level. Mr. Henry Black (Maintenance Unit - Analysis Section Squad Leader) and Mr. Garland Haywood (Division 10 Bridge Maintenance Engineer) are graciously assisting in this project. The project will provide valuable information on the correlation between predicted and actual bridge behavior under both controlled truck loading and general traffic conditions.</FONT></P>
Lin WigginsMrinmay "Moy" BiswasJuly 2001 - June 2003
102
Complete
1
2003-08
47
  
661NC-01-01Structures & ConstructionComposite & Innovative MaterialsGlass Fiber Reinforced Polymer Bridge Deck - (Innovative Bridge Research and Construction Program)
<P><FONT face=Verdana size=2>The 20th century brought about many innovative changes to the world of construction. While concrete and steel tend to be the materials of choice, technology has introduced a material, which may become the material of choice for future designs. This material is Fiber Reinforced Polymer (FRP). Composites being both light and strong, are being introduced to many applications, including bridge construction.<BR><BR></FONT><FONT face=Verdana size=2>In an effort to speed construction and increase service life of a bridge, the North Carolina Department of Transportation (NCDOT) looked to composites. A deteriorating bridge in Union County presented the opportunity to test this new concept in bridge construction. Bridge #89-022 over Mill Creek on New Salem Road (SR1627) needed to be removed and rebuilt, so it was chosen to receive the first composite deck in the State of North Carolina. Martin Marietta Composites division, producer of the FRP DuraSpanTM system, was contracted to produce the panels required for the bridge replacement. <BR><BR></FONT><FONT face=Verdana size=2>The construction of this bridge was funded in large part through a discretionary grant from the FHWA through the Innovative Bridge Research and Construction Program. Evaluation of this structure continues as a part of the </FONT><FONT face=Verdana size=2><STRONG>NCDOT Research Project2002-12 titled "Evaluation of Bridge Analysis vis-à-vis Performance". The results of this evaluation will therefore be contained in the final report for this research to be concluded in the summer of 2003.</STRONG></FONT><BR><BR></P><br><P><FONT face="Verdana, Arial, Helvetica, sans-serif" size=2><FONT face=Verdana size=2>First, the existing structure was removed, and the new steel girders were installed. Then, angles were welded to the girders to support the panel and to provide room for grout injection. After the angles were welded in place, the panels were placed in accordance with the Martin Marietta Installation Guide by NCDOT personnel, and under the supervision of Martin Marietta representatives. After the deck panels were placed, a combination of shear studs and grout were used to permanently attach the panels to the girders. Once this attachment was made, the rebar and forms for the endwalls were placed, and the concrete was poured. The asphalt overlay was then placed followed by the guardrail. The last item on the agenda was the load testing of the bridge. Once testing was completed, the bridge was opened to traffic.</FONT><BR></FONT><FONT face="Verdana, Arial, Helvetica, sans-serif"></FONT></P>
Mrinmay "Moy" BiswasSeptember 2001 - November 2001
101
In Progress
1
not yet assigned
48
  
681132002Structures & ConstructionMiscellaneousLateral Capacity of Drilled Shafts Embedded in Soft Weathered Rock (SWR) Profiles
<P><FONT face=Verdana size=2>In areas of weathered and decomposed rock profiles, the definition of the soil parameters needed for the analysis and design of laterally loaded drilled shafts poses a great challenge for engineers and contractors. The lack of an acceptable analysis procedure is compounded by the unavailability of a means for evaluating the weathered profile properties, including the lateral rock modulus, which often leads to the over-conservative design of the shaft foundation.</FONT></P><br><P><FONT face=Verdana size=2>One of the most acceptable methods to design a laterally-loaded shaft is the P-y curve approach. In order to develop P-y curves in soft weathered rock, four complementary approaches have been followed. One is the Finite Element method of modeling using a computer program called ABAQUS for 3-dimensional analytical modeling of resistance forms. The second is laboratory work to model the characteristics of P-y curves in the soft weathered rock. The third is field testing using full-scale shafts to develop and verify P-y curves in the soft weathered rock. Finally, Class A performance predictions are calculated using the development of the model.</FONT></P><br><P><FONT face=Verdana size=2>This research reveals that none of the current proposed P-y curve approaches to design-drilled shafts embedded in soft weathered Piedmont rock profile can reasonably estimate the load-versus-deflection characteristics of a laterally loaded shaft.</FONT></P><br><P><FONT face=Verdana size=2>A new concept of the point of rotation has been developed based on measured profiles from field and laboratory tests, and F.E.M. analysis to define the load-deflection characteristics of drilled shaft embedded in soft weathered rock. A method to evaluate stiffness properties of the soft weathered rock by utilization of the in-situ testing device, the rock dilatometer, as well as a method based on the information of joint conditions, RQD, and the strength properties of cored samples are proposed.</FONT></P><br><P><FONT size=2><FONT face=Verdana>The proposed P-y curve model for soft-weathered rock closely agrees with field test results, which are performed in various rock profiles, and also the proposed method is verified by comparisons with published test results.</FONT> </FONT></P>
Mohammed MullaMrinmay "Moy" BiswasJuly 2001 - June 2002
102
Complete
1
2002-08
49
  
682142002Structures & ConstructionMiscellaneousLoad Resistance Factor Design (LRFD) for Reliability Analysis/ Design of Driven Piles Axial Capacity
<P><FONT face=Verdana size=2>The conventional design methodology for axially loaded pile foundation utilizes a Factor of Safety to account for the uncertainty associated with various design variables. This practice, however, does not address uncertainty in a consistent and rational manner. The Load and Resistance Factor Design (LRFD) method utilizes load and resistance factors to account for uncertainty. These factors are obtained from the analysis of reliability of the soil/foundation system. Guidelines published in AASHTO (1994) call for the implementation of the LRFD method for bridges. Driven piles are commonly used for support of bridge foundation and the need to define the resistance factors for their design is urgent. AASHTO guidelines provide these factors for general soil conditions but these general factors are not appropriate for specific local conditions. Documentation in literature indicates that several users found that the AASHTO-recommended factors lead to inappropriate design conflicting with their experiences.</FONT></P><br><P><FONT face=Verdana size=2>The objective of the proposed study is to develop the resistance factors for the design of driven piles in North Carolina. AASHTO guidelines provide resistance factors that are reportedly inappropriate for the various regions of North Carolina. The resistance factors will be developed for the unique soil types of this state. These factors will be developed in the framework of 'reliability analysis' using PDA and static load test data embodying the uncertainty associated with soil parameters. The form of probability distribution function describing the pile resistance will be studied and the associated parameters will then be quantified. First order reliability method will then be used to formulate the relationship between the factors and the reliability.</FONT></P><br><P><FONT face=Verdana size=2>A detailed LRFD procedure will be developed and presented. Parametric and comparative studies will be conducted to evaluate the effective pile length, pile capacity, and blow count criteria based on soil and pile properties. NCDOT engineers will be trained in the developed LRFD method.</FONT></P>
Mohammed MullaMrinmay "Moy" BiswasJuly 2001 - June 2002
102
Complete
1
2005-08
50
  
422192002EnvironmentWetlands MitigationAssessment of the Groundwater Flows at Juniper Bay and their Impact on the Surrounding Area
<P><FONT face=Verdana size=2>This proposal is a supplement to the work already underway on the Juniper Bay wetland restoration project in Robeson County. Preliminary data from the Juniper Bay wetland restoration study suggests that significant flows of groundwater are both entering and leaving the bay. Due to the sparseness of the data currently being collected, any estimate of the subsurface flows based on those data would be crude. An assessment of the role of the groundwater flows in the hydrologic behavior of the project site and its impacts on the surrounding area depends strongly on a reasonably accurate picture of what is happening at the perimeter of the bay.<BR><BR></FONT><FONT face=Verdana size=2>The objectives of this research are to:</FONT><BR></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Characterize the subsurface flows at four locations on the perimeter of the project site.</FONT></FONT></LI><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Determine the degree and modes of interaction of the perimeter ditch with the partially confined sand strata.</FONT></FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Model the subsurface flows in the Juniper Bay area and assess the impacts of those flows on the area immediately surrounding the bay.</FONT></FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Develop management recommendations for minimizing off-site impacts at Juniper Bay and extrapolate findings to provide guidelines for assessment of the likelihood of hydraulic trespass on wetland conversion sites in general.</FONT> </FONT></LI></UL>
Jim HauserG. Dennis PipkinMay 2002 - April 2005
102
Complete
1
2006-19
51
  
701042003EnvironmentWater Quality and Pollutant DischargeMinimizing Water Quality Impacts of Road Construction
<FONT face=Verdana>Highway construction usually requires large areas of disturbance in order to be cost efficient. This creates the potential for accelerated erosion and impacts on local streams and lakes. Additional tools, or Best Management Practices, need to be tested, demonstrated, and refined to obtain reductions in sediment and, in particular, turbidity beyond current practices. </FONT><BR><BR><br><P><FONT face=Verdana size=2>This research targets increasingly stringent turbidity limits in runoff as imposed by NCDENR. Of particular concern is the water quality of runoff from the construction of <BR>I-485 around Charlotte and the impact of runoff on nearby watersheds. Work will be coordinated with the primary Contractor. </FONT></P><br><P><FONT face=Verdana size=2>The Objectives of the project are to:</FONT></P><br><OL><br><LI><FONT face=Verdana size=2>Compare a variety of erosion control systems for effectiveness, including combinations of standard straw, polyacrylamide, rolled erosion control products, and bonded fiber matrix hydromulching </FONT><br><LI><FONT size=2><FONT face=Verdana>Install, evaluate and improve systems to increase sediment and turbidity control in standard and modified traps and basins</FONT> </FONT><br><LI><FONT face=Verdana size=2>Establish baseline information on stream water quality and stability in small watersheds as affected by the installation of standard and innovative erosion, sediment and turbidity control systems </FONT><br><LI><FONT size=2><FONT face=Verdana>Establish stream water quality and stability in small watersheds which are impacted by NCDOT and, by comparison other commercial/residential development</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Establish the current stability of Long Creek and four tributaries and measure changes annually</FONT> </FONT><br><LI><FONT face=Verdana size=2>Conduct annual benthic macroinvertebrate and habitat surveys at five points along Long Creek and in two tributaries </FONT><br><LI><FONT size=2><FONT face=Verdana>Conduct workshops, demonstration, and training for staff from NCDOT, NCDENR, local programs, and private contractors</FONT> </FONT></LI></OL><br><P><FONT face=Verdana size=2>The project is significant in that it will provide an evaluation of various methods to reduce erosion and off site movement of sediment and turbidity on large, active construction sites. We will test and improve, as needed, several new sediment trap and basin designs to minimize sediment and turbidity at their outlets using PAM and modifications to the typical rock outlet. It will also be important to monitor water quality and stream stability as impacted by different levels of erosion and sediment control efforts during active disturbance. </FONT></P>
David HarrisG. Dennis PipkinSeptember 2002 - August 2005
102
Complete
1
2006-21
52
  
702052003PlanningFacility DesignEffects of Increased U-Turns at Intersections on Divided Facilities and Median Divided versus Five-Lane Undivided Benefits
<FONT face=Verdana>A great debate is raging within the NCDOT and the public about four-lane divided versus five-lane undivided cross-sections for urban and suburban arterials. Four-lane divided cross-sections seem to be safer, based on collision rates from existing facilities in North Carolina (NC). Four-lane divided cross-sections are also more aesthetic and provide better midblock levels of service. However, five-lane cross-sections allow direct access from both directions into adjacent properties, and are thus favored by landowners, developers, and many local government officials. Five-lane cross-sections are narrower, and thus may save on construction costs. Five-lane cross-sections may also have safety and capacity advantages at some intersections due to fewer u-turns than with four-lane divided cross-sections. </FONT><br><P><FONT face=Verdana size=2>The purpose of this project is to provide the NCDOT with the best possible up-to-date, NC-specific information on the rival cross-sections. The project team will calibrate a collision model for each type of cross-section using NC collision data. The collision model will include terms of driveway densities and other factors, which allow the model to make much more credible predictions about the safety of future roads than can be made currently using statewide collision rates. The project team will also collect operational and safety data at intersections on four-lane divided cross-sections where significant volumes of u-turns are present to see whether those u-turns actually cause the problems attributed to them.</FONT></P><br><P><FONT face=Verdana size=2>The main product from the project will be a easy-to-use four-page brochure with the collision model, u-turn results, and other facts about the rival cross-sections. Planners, designers, local officials, and others will be able to use the brochure to simply compare the cross-sections and arrive at the safest, most efficient, and most cost-effective choice for a particular situation. The project team will also produce a detailed research report.</FONT></P><br><P><FONT face=Verdana size=2>The primary objectives of the research study are to:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Develop a collision model validated with NC data for sections of four-lane-with-median and five-lane highways between signals.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Identify the operational impacts of u-turns on a divided four-lane highway.</FONT> </FONT></LI></UL>
James H. DunlopG. Dennis PipkinJuly 2002 - June 2004
102
Complete
1
2004-07
53
  
703062003Traffic & SafetyITS and Incident ManagementIncident Management and Assistance Patrols: Assessment of Investment Benefits and Costs
<P><FONT face=Verdana size=2>Incident Management Assistance Patrols (IMAP) are vital in dealing with traffic, benefiting the public in terms of motorist assistance/customer satisfaction, incident management, reduction in incident-induced delay, reduction in secondary incidents, higher throughput, improved safety, lower energy use and lower emissions. IMAP have been implemented in many large urban areas including Los Angeles, Chicago and Houston, with benefit-cost ratios that range from 3:1 to 23:1. They have also been implemented in 5 North Carolina contexts, including the Triangle and Charlotte. While the system in Charlotte is reported (in 1993) to have benefit-cost ratios between 3:1 and 7:1, there is a need to quantify benefits of existing IMAPs and identify potential for other North Carolina IMAP expansion and implementation. North Carolina has close to 200,000 police-reported crashes yearly and many more non-crash incidents e.g., vehicles run out of gas, stall or are hindered by debris on road. Presently, the 5 IMAP programs in NC cover only a fraction of these crashes and incidents, e.g., that made about 45,000 stops across the state - and over 50% including assisting disabled motorists. There are many NC areas that may present good IMAP deployment opportunities, allowing us to move towards implementing intelligent transportation systems. However, there is a need to identify which of the potential sites should receive the highest priority for IMAP implementation. This study will therefore:</FONT></P><br><UL><br><LI><FONT face=Verdana size=2>Review service patrols benefit-cost literature and synthesize their finding to explore implications for North Carolina. </FONT><br><LI><FONT face=Verdana size=2>Develop criteria to identify IMAP expansion opportunities within NC, i.e., IMAP should be expanded to cities or counties that will benefit the most. These are perhaps those experiencing higher incident/crash frequency, more traffic on roadways, more injurious crashes (i.e., higher total K &amp; A injury crashes and higher K&amp; A crashes per million vehicle miles), longer incident detection times, longer response times and clearance times, low levels of motorists assistance, poor incident management, and worsening air quality; we will inventory incident and crash data that can help identify opportunities for expanding IMAP to "high-impact" areas within NC. </FONT><br><LI><FONT face=Verdana size=2>Utilize detailed NC data on traffic demand, capacity, incidents and hypothetical IMAP attributes (miles patrolled per day, number of IMAP vehicles, number of incident responses per day and response times) in the "high-impact" areas, along with a traffic model (FREEVAL) to assess the benefits of IMAPs. </FONT></LI></UL><br><P><FONT face=Verdana size=2>Based on the North Carolina Highway Safety Information System (HSIS) crash data and inventory data (which includes geometric information and daily traffic) and other data sources, we will explore IMAP program opportunities in geographical areas such as cities and counties. In addition, we will review the field date requirements and relevant products (e.g., hardware and software) that will be appropriate for NC. We will obtain cost estimates from the federally maintained benefit-cost database.</FONT></P><br><P><FONT face=Verdana size=2>The primary objectives of the research study are to:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Quantify benefits and costs of existing IMAPs in North Carolina.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Identify opportunities for IMAP initiation and expansion in North Carolina.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Identify the field data requirements for incident management and relevant hardware/software.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>NCDOT will be able to use this research to:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Quantify the benefits and costs of existing IMAPs to
Robert StoneMustan KadibhaiJuly 2002 - June 2003
102
Complete
1
2005-02
54
  
704072003PlanningFacility DesignFalse Capacity for Lane Drops
<P><FONT face=Verdana size=2>The practice of discontinuing a through or shared lane at the downstream side of a traffic signal is quite common on North Carolina's streets and highways. That additional lane (sometimes called auxiliary lane) is intended to increase the capacity of the intersection approach. That presumption is true only if <EM>drivers will use that lane efficiently both on the upstream and the downstream end of the intersection</EM>. Inefficient use of the lane at the upstream end will result in a false calculation of capacity since many drivers may shy away from using the lane as they anticipate the urgent need to merge to the continuous lane at the downstream end. Thus, the auxiliary lane may not produce the full capacity it is meant to provide. Inefficient use of the lane on the downstream end could result in a safety hazard, particularly if the design of the downstream side is inadequate to handle the merging traffic. Thus, these types of lane design have both operational and safety concerns that need to be addressed in the early stage of the design process.</FONT></P><br><P><FONT face=Verdana size=2>Currently there is no mechanism by which the degree of lane utilization can be related to the design features and surroundings of the auxiliary lane (i.e., downstream full lane length, taper length, signing, driveways, etc.). The Highway Capacity Manual (HCM) provides default values for lane utilization but these are based strictly on the number and type of approach lanes, and do not take into account the disposition of the lanes(s) downstream of the signal. Further, the HCM deals with lane groups as opposed to individual lanes. The SIDRA model, now used for the analysis of isolated signalized intersections in North Carolina, provides a lane-by-lane utilization factor, which can be calibrated using field data. Regardless of which model is used, the empirical database to calibrate the lane utilization factor is simply non-existent.</FONT></P><br><P><FONT face=Verdana size=2>The purpose of this study is to collect operational and safety-related data at intersection approaches that have auxiliary lanes. The data will be used to study will develop a lane utilization prediction model, which will take into account, among other things, the design features of the downstream lane drop. Also, the safety data will identify those lane design aspects that appear to promote safety and provide a smoother merging process. These two outcomes will result in an appropriate capacity estimation procedure for such design in North Carolina, and in the promotion of safe and efficient designs when such lanes are specified. The results from the study will be summarized in two tables for easy use by NCDOT personnel in capacity analyses and designs.</FONT></P><br><P><FONT face=Verdana size=2>The primary objectives of the research study include the development of:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>A set of field-verified estimates for the lane utilization factor at a signalized intersection when there is a downstream lane drop.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Estimated collision rates for lane drop areas around signalized intersections, including lane drops at the intersection.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>The results from this research will be used by Traffic Engineering, Roadway Design, and other units of the NCDOT. For new designs or existing cases, they will be able to apply proper values of the lane utilization factor when conducting capacity analyses of intersections with auxiliary lanes. The lane utilization factor could be extremely critical in proper functioning of the intersection, changing the estimated capacity by 20 percent or more in some cases. This could be enough to add thousand of hours of delay per year to an intersection with a poorly designed lane drop. Since there are hundreds of these locations around the state, this is a very significant issue
Gary FaulknerMustan KadibhaiJuly 2002 - June 2004
102
Complete
1
2005-01
55
  
721082003Pavement & MaintenanceVegetation Management and RoadsideApplication Placement Technologies for Vegetation Management on North Carolina Roadsides
<P><FONT face=Verdana size=2>Beginning in 1995, NCDOT has been in the process of converting eastern and piedmont rights-of-way from traditional species including tall fescue (<EM>Festuca arundinacea</EM>) to centipedegrass (<EM>Eremochloa ophiuroides</EM>), a turf species that requires less maintenance. Plant growth regulators (PGR) have also been implemented into the vegetation management plan on tall fescue and bahiagrass (<EM>Paspalum notatum</EM>) roadsides which make up 55% and 27%, respectively. By utilizing PGRs, vegetative growth is reduced. </FONT></P><br><P><FONT face=Verdana size=2>Centipede grass is a low maintenance turf species, which prefers acid soils and minimal fertility, conditions typically found on roadsides. Allowed to grow naturally, centipede grass reaches a mature vegetative height less than eight inches, creating a no-mow situation.</FONT></P><br><P><FONT face=Verdana size=2>Research has shown that, if the application of a PGR is performed in a timely manner, vegetative and seedhead suppression is achieved. Utilizing PGR programs, the number of mowing cycles can be reduced from five to two or three cycles per growing season and in the case of bahiagrass, seedhead production is totally eliminated if applied in a timely manner. This allows maintenance budgets to be reduced while safety is increased to motorists and NCDOT employees.</FONT></P><BR><br><P><FONT face=Verdana size=2>Centipede grass has been successfully established in many of the areas throughout the piedmont and coastal plain of NC and has reduced maintenance inputs. However, broomsedge (<EM>Andropogon virginicus</EM>), a clump forming perennial weed has invaded many of these areas. Broomsedge, when allowed to grow, reaches a mature height between 18 and 36 inches. The areas contaminated with broomsedge are aesthetically unpleasing and safety is decreased in these areas. Where centipedgegrass is the primary desirable turf, the only current option is to mechanically mow the areas contaminated with broomsedge. This practice only reduces the foliar growth temporarily and does not reduce the population. Again this is the only management option available as no selective herbicide exists, registered or experimental, that controls broomsedge without harming centipedegrass.</FONT></P><BR><br><P><FONT face=Verdana size=2>However, much research has focused on pesticide placement technologies. Commercially available equipment which utilizes this technology includes the Burch Wet Blade, the Weed Bug, and the Brown Brush Monitor. The Burch Wet Blade and the Weed Bug function based on a height differential between the targeted weed species and the desirable turf. The Brown Brush Monitor does not use the height differential and rather combines mowing and herbicide treatment in a single pass. The Burch Wet Blade and Weed Bug may offer a solution to broomsedge control in centipedegrass, however no data is currently available either supporting or opposing this claim.</FONT></P><BR><br><P><FONT face=Verdana size=2>With increased use of PGRs on roadside for reducing maintenance inputs and mowing cycles, application placement technologies may also prove beneficial. Application of PGRs through application placement technologies would not rely on a height differential and rather on a uniform coverage of the PGR on the desired turf grass species. Again broadcast applications of selected PGRs have been shown to significantly reduce maintenance costs. Also, with the limited amount of knowledge currently available about these systems, the potential exists for additional savings if more pesticide is absorbed into the plant through the cut surface as opposed to a broadcast application where the PGR is applied and environmental conditions, weather conditions, etc. may inhibit uptake and translocation.<BR><BR>The primary objectives of the research study are to:</FONT></P><BR><br><UL><BR><br><LI><FONT size=2><FONT face=Verdana>Compare the Burch Wet Blade and the Weed Bug
Don LeeErnest MorrisonJuly 2002 - June 2005
102
Complete
1
2006-42
56
  
722092003Pavement & MaintenanceAsphalt Mix DesignTypical Dynamic Moduli for North Carolina Asphalt Concrete Mixes
<P><FONT face=Verdana size=2>Recent findings from research projects under the auspices of the National Cooperative Highway Research Program (NCHRP) clearly emphasize the importance of dynamic modulus testing of asphalt mixes. This single material property, the dynamic modulus of asphalt concrete, will be used as the key parameter in the 2002 AASHTO Design Guide as well as in the Superpave simple performance test protocol that complements the volumetric mix design. The release of the new AASHTO pavement design guide in 2002 makes it urgent to obtain dynamic moduli values of typical asphalt mixes used in North Carolina.</FONT></P><br><P><FONT face=Verdana size=2>The objective of this study is to develop a database of dynamic moduli values and their variability for asphalt mixes used in North Carolina using both the uniaxial compression test and the indirect tensile test. In addition to the dynamic modulus testing of the representative mixes, surrogate methods will be evaluated, including the impact resonance method and Witczak's predictive equation. These methods may be acceptable for the design of mixes and pavements that are normally subject to low traffic volume.</FONT></P><br><P><FONT face=Verdana size=2>The dynamic modulus database to be developed from this project will allow the NCDOT Pavement Management Unit (PMU) to evaluate the new AASHTO pavement design guide in the short term and will provide necessary input for the design of asphalt pavements using the new design guide in the long term. Also, this database will provide necessary information to use the dynamic moduli values in forensic studies and overlay design. The experience and database obtained from this research will also help the NCDOT Materials and Tests Unit (M&amp;T) implement the dynamic modulus testing in its own laboratory.<BR><BR>The primary objectives of the research study are to: </FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Develop a database for typical dynamic moduli values and their variability for asphalt concrete mixes used in North Carolina.</FONT> </FONT><br><LI><FONT face=Verdana><FONT size=2>Develop/evaluate a simple surrogate test or prediction method for determination of the dynamic moduli of asphalt mixes.<BR><BR>The following primary products are expected from this research study:</FONT><BR></FONT><br><LI><FONT size=2><FONT face=Verdana>A database containing the values and variability of dynamic moduli.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>A refined complex modulus test protocol that is in accordance with the recommendations from the NCHRP 9-19 and 9-29 research teams.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>A verified or calibrated form of Witczak's predictive equation for the dynamic modulus.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>The relationship between the dynamic modulus measured from the complex modulus testing and the dynamic modulus of elasticity measured from the impact resonance method.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>The relationship between the dynamic modulus measured from the uniaxial compression testing and that measured from the indirect tensile testing.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>The products from the research study will be implemented by the NCDOT Pavement Management Unit to evaluate the new 2002 AASHTO pavement design procedure for applicability to North Carolina pavements. The experience and database obtained from this research will be shared with the NCDOT Materials and Tests Unit to help the implementation of the complex modulus testing in the lab.</FONT></P>
Judith Corley-LayMustan KadibhaiJuly 2002 - June 2004
102
Complete
1
2005-03
57
  
741102003Pavement & MaintenanceAsphalt Mix DesignDetermination of Optimum Gradation for Resistance to Permeability, Rutting, and Fatigue Cracking
<P><FONT face=Verdana size=2>With the new Superpave mix design system in use today, more and more coarse graded mix designs are being used. With these coarse graded mixes, there are more interconnected voids in the pavement layers, causing higher permeability. These permeable pavements allow water to pass through them and cause premature failures. Thus, it is important that gradations be developed for surface course mixtures, which are coarser in nature with fewer interconnected voids so that their performance is not affected by the moisture damage.</FONT></P><br><P><FONT face=Verdana size=2>The Bailey method is proposed to be used for analyzing the packing characteristics of a blend of aggregates. The Bailey method of Gradation Analysis presents the foundation for a comprehensive gradation evaluation and modification procedure. It outlines a method to combine aggregates that provide interlock as the backbone for the aggregate skeleton. Aggregate ratios, which are based on particle packing principles, are used to analyze the particle packing of the overall aggregate structure.</FONT></P><br><P><FONT face=Verdana size=2>This study will provide a sound methodology of modifying surface course mixture gradations to yield low permeability and superior performance. A band of gradations will be recommended meeting the criteria of low permeability and superior performance. In order to ensure quality performance of pavements, the mixtures made with modified gradations and having low permeability will be evaluated in terms of their resistance to rutting and fatigue cracking using the Simple Shear Tester and the Asphalt Pavement Analyzer.</FONT></P><br><P><FONT face=Verdana size=2>The primary objectives of this study are to:</FONT></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Select several 12.5 mm and 9.5 mm mixtures with gradations on the coarser side and review their void structures and permeability characteristics.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Modify the gradations of the above mixes, using the Bailey Method, to arrive at the desired void structure.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Evaluate the developed gradations in terms of permeability and other performance characteristics, e.g. rutting and fatigue characteristics.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Evaluate the effect of air voids on permeability characteristics at 4% and 7% air voids.</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>Recommend a gradation band that will have low permeability as well as high resistance to rutting and fatigue cracking.</FONT> </FONT></LI></OL>
Cecil JonesMustan KadibhaiJuly 2002 - June 2004
102
Complete
1
2004-12
58
  
761112003PlanningPublic & Rural TransportationRailroad Crossing Wayside Horn Evaluation
<P><FONT face=Verdana size=2>Locomotive horn noise is a growing concern throughout the country. Currently there is a national proposed rule making that will allow communities to designate quite zones where trains do not sound horns at crossings that have enhanced protection. The Triangle Transit Authority has proposed a quiet zone for the 30-mile regional rail project corridor between Raleigh and Durham and it is expected that many North Carolina communities may seek to follow their lead. Providing enhanced protection at crossings is expensive and cannot be afforded by most communities. In addition, there is a safety concern. The locomotive horn is a proven and effective audible warning device that augments the visual traffic control devices at highway-railroad crossings. Elimination of this integral part of the crossing safety system has been proven to reduce safety.<BR><BR></FONT><FONT face=Verdana size=2>However, there is a potential solution. A commercially available wayside horn has been developed to replace the locomotive horn. This stationary horn, mounted at the crossing, directs the sound down the intersection roadways rather than along the track. The directional horn can operate at a lower sound level and covers far less adjacent community area. This research project will test and evaluate the wayside horn as an alternative to quite zones.</FONT><BR></P><br><P><FONT face=Verdana size=2>This study will be carried out in two parts: a field study and opinion survey. Field studies will be conducted at two highway-rail intersections. Data on driver behavior will be collected by direct observation and with the aid of video cameras before installation of the wayside horn and after installation of the horn. Community response to the wayside horn will be determined by a mailed questionnaire. Community response to the wayside horn will be determined by a mailed questionnaire and/or personal interview.</FONT><BR></P><br><P><FONT face=Verdana size=2>Based upon the research results, recommendations will be made as to whether or not a wayside horn is an acceptable alternative to a quiet zone. The recommendations will consider safety, community concerns, and cost.</FONT></P>
Paul C. WorleyErnest MorrisonJuly 2002 - June 2004
102
Complete
1
2006-36
59
  
762122003PlanningTraffic Surveys, Modeling and ForecastingNorth Carolina Level of Service Program
<P><FONT face=Verdana size=2>Accurate travel demand modeling requires accurate values for roadway capacities and service volumes at various levels of service. The NCDOT Statewide Planning Branch (SWP) does not currently possess a consistent method for determining expected service volumes and capacities for a given set of roadway, geographic, traffic, or other characteristics. </FONT></P><BR><br><P><FONT face=Verdana size=2>Some guidance does exist concerning these critical planning values. The Florida Department of Transportation (FDOT) has developed a revised LOS handbook. The United States Highway Capacity Manual (HCM), published by the Transportation Research Board and revised in 2000, does provide planning methodologies for various facilities. However, the paucity of information typically available at the planning stages coupled with the relative complexity of the HCM product make direct use of the HCM impractical or inefficient for forecasting applications. Unfortunately, the tools currently available to SWP are either too broad, too complex, not consistent, or not adapted to North Carolina conditions.</FONT></P><BR><br><P><FONT face=Verdana size=2>The North Carolina Level of Service (LOS) Program described in this proposal is designed to remedy a planning capability deficiency for the Department. This project proposes to develop a user friendly computer program that will provide users with accurate, consistent expected hourly service volumes and expected daily traffic for various facilities, tailored to North Carolina conditions.</FONT></P>
David S. WassermanG. Dennis PipkinJuly 2002 - June 2004
102
Complete
1
2006-06
60
  
781132003PlanningTraffic Surveys, Modeling and ForecastingTraditional Neighborhood Development Trip Generation Study
<P><FONT face=Verdana size=2>Traditional Neighborhood Development (TNDs) are characterized by human-scale walkable and transit friendly communities with moderate to high densities and a mixed-use core. TNDs are becoming increasingly popular in the United States and they are expected to encourage the use of alternative modes and increase internal trip capture ultimately reducing congestion, Vehicle Miles Traveled and improving air quality. There is empirical evidence that people are willing to pay a premium to live in TNDs (Tu and Eppli 2001). This study will assess if trip generation rates and alternative mode use are indeed different in TNDs compared to those predicted by conventional ITE methods. To do this, the study will:</FONT></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Review studies on the impacts of TNDs conducted in other geographical areas and synthesize their findings to explore implications for North Carolina.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Collect and use North Carolina data -- by conducting a resident survey of Southern Village TND in Orange County -- to explore the impacts of TNDs in terms of trip generation, trip chaining, mode choice, and activity participation. </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Conduct surveys of on-site office workers or off-site visitors to the Southern Village to understand the travel characteristics of office and retail users. </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: Verdana"><FONT face=Verdana size=2>Collect relevant non-survey data from traffic counts to compare it with survey data. </FONT></LI></OL><BR><br><P><FONT face=Verdana size=2>We will conduct behavioral surveys/travel diaries to explore how travelers¿ behavior is influenced by TNDs. The survey results will be compared with the ITE¿s Trip Generation Manual and to trip generation rates from a nearby conventional neighborhood. Analysis of the data will be able to identify TND effects. A related purpose of the surveys is to establish a benchmark/baseline of traveler behavior in TNDs and to provide data for future comparisons and modeling efforts (Southern Village can serve as a future Laboratory or Testbed for transportation experiments).</FONT></P><BR><br><P><FONT face=Verdana size=2>The benefits of the study will be to understand (1) the extent to which TNDs reduce vehicular trips produced by residents and internally capture some of them, and (2) what other trips are attracted to TNDs. This will ultimately generate useful information in future transportation planning activities with North Carolina. The survey participants will be selected randomly, and we will obtain a statistically significant sample size. The data will be analyzed using state-of-the-art methods (category analysis and trip generation modeling) and it will be available to various branches at NC DOT. Ultimately this study will allow us to make more informed judgments about TND development and traffic impact analysis.</FONT></P>
Harrison MarshallG. Dennis PipkinJuly 2002 - June 2003
102
Complete
1
2005-05
61
  
782142003Structures & ConstructionConcreteCorrosion Inhibitors for Concrete Bridges
<P><FONT face=Verdana size=2>Deterioration of concrete bridges is a continuing problem facing the NCDOT. Use of deicing salts in the western part of the state and humidity and salty conditions in the eastern part of the state cause premature deterioration of concrete bridge elements. This premature deterioration results in a financial burden on the NCDOT's maintenance budget, negative psychological effects on highway users, increased traffic delays during maintenance and reconstruction, potential safety hazards, and reduced service life of bridges.</FONT></P><BR><br><P><FONT face=Verdana size=2>A number of corrosion inhibitors claim to delay, slow, stop, or even reverse the corrosion process in existing concrete structures. Such claims have not been fully verified through independent and comprehensive studies, and specifically for the conditions and problems facing the NCDOT.</FONT></P><BR><br><P><FONT face=Verdana size=2>The proposed study would complement the existing and on-going research by providing realistic accelerated test data to compare the effectiveness of six, surface-applied corrosion inhibitors on concrete specimens with different levels of chloride contamination and subjected to different environmental conditions. The study will establish threshold chloride content, beyond which surface treatments are not useful. Also, the products will be evaluated for any possible detrimental effects on concrete, and any potential application problems. Guidelines and specifications will be developed for surface treatment using corrosion inhibitors, and recommended means to incorporate surface treatments within the state bridge inspection and maintenance program. Means for technology transfer will be recommended, as well as future field applications and validations with continuous monitoring. </FONT></P>
Cecil JonesMrinmay "Moy" BiswasJuly 2002 - June 2004
102
Complete
1
2006-25
62
  
801152003Structures & ConstructionMiscellaneousJetting Techniques for Pile Installation and Environmental Impact Minimization
<P><FONT face=Verdana size=2>Due to environmental concerns, regulatory agencies are opposing, or in some cases, prohibiting the use of jetting for pile installation. Under the correct conditions jetting is an effective and economical method of pile installation. Currently, no rational criteria or specific guidelines are available to assess the environmental impact and to ensure the preservation of environmental sensitive areas during pile jetting. The NCDOT has experience with bridge projects where without jetting, pile foundations could not be used and the cost of construction escalated significantly. </FONT></P><BR><BR><br><P><FONT face=Verdana size=2>The jetting process can be considered to affect the hydric soil layer within the pile installation profile. The ecological impact of the jetting installation method can be measured by the disturbance caused to the hydric layer in terms of zone of extent as well as thickness of the disturbed zone. Assessment techniques such as Habitat Evaluation Procedure (HEP) and Wetland Evaluation Technique (WET) can evaluate the impact of this hydric layer disturbance on aquatic and vegetative ecosystems.</FONT></P><BR><BR><br><P><FONT face=Verdana size=2>The objective of this research is to characterize and define disturbance due to jetting as manifested by the zone of influence and volume of the debris area. This disturbance will be defined as a function of jetting pressure, flow rate, and site conditions including soil types with specific emphasis on hydric soils. Second, draft specifications will be developed with recommendations regarding jetting parameters to minimize disturbance as well as possible conjugate practice modification of the jetting procedure with such addition of vacuum and/or water extraction/circulation techniques.</FONT></P>
Mohammed MullaG. Dennis PipkinJuly 2002 - June 2004
102
Complete
1
2006-09
63
  
821162003PlanningLand Use PlanningThe Connection between Land Use and Transportation in Land Use Plans
<P><FONT face=Verdana size=2>By examining how local land use plans anticipate and account for transportation projects and how related land management tools are actually being used by county and municipal governments in North Carolina, this study examines the degree to which indirect and cumulative land development impact assessments done for a proposed transportation project within a given locality could build on that locality's land use plan. Data for the study came from a survey of all counties and selected municipalities in the State, from planned transportation investments for all communities in the State for the 2004-2010 period and from an evaluation of 30 local plans from communities that have land use plans. The results suggest that transportation and land use planning are not as coordinated as they could or should be in land use plans. The absence of this coordination in land use plans limits the ability of planners to anticipate urban development from transportation investments. This lack of integration also means that assessments of indirect land development impacts of projects generally can not rely solely on local land use plans. Land use plans can be used a starting point for such assessments, but additional reliance on the plans requires that they incorporate the development impacts of transportation projects in a more systematic fashion. Recommendations include the provision of technical assistance for improving land use plans with respect to transportation; developing best-practice reports highlighting the use of land use and transportation indicators at different levels of aggregation and under different growth conditions; and strengthening regional and State Agencies in their ability to reach out to local land use planners to increase collaboration among parties and improve planning outcomes. This will enable localities to develop more transportation-aware land use plans.</FONT></P>
G. Dennis PipkinJanuary 2003 - March 2004
102
Complete
1
2004-08
64
  
841172003EnvironmentWater Quality and Pollutant DischargeDevelopment of a GIS-Based Methodology to Estimate Stormwater Runoff Pollutant Loadings from North Carolina Highways
<P><FONT face=Verdana size=2>This research aims to develop statistical relationships between pollutant loadings and climate and traffic data. More importantly, the research will develop a methodology by which we can estimate pollutant loadings on a highway segment or watershed basis. The methodology will be GIS based to superimpose the various effects of the roadway to establish the loadings on a segment or basin basis. The methodology will help identify Best Management Practices on a case-by-case basis as required in the NPDES requirements.</FONT></P><br><P><FONT face=Verdana size=2>UNC Charlotte researchers were contracted by NCDOT to monitor and characterize pollutants in highway runoff from several roadway sites across North Carolina as part of our NPDES (National Pollution Elimination Discharge System) permit requirements. This data will be used to develop a statistical relationship between runoff water quality and climate, traffic and physiographic road conditions (traffic and roadway maintenance activities) in order to predict pollutant loadings for the roadways across the State. The predictive relationships will then be applied to a GIS platform that could be used to predict NPS road source pollutant loadings for the various physiographic regions.</FONT></P><br><P><FONT face=Verdana size=2>The goal is to provide an automatic, scientifically based model (GIS NPS platform or model) that can be used: to calculate basin wide pollutant loadings from roadway corridors; to prioritize outfall sensitive water quality sites to determine the installation of Best Management Practices (BMP's) to treat highway runoff; and to compare the estimated GIS NPS data with existing estimates of NPS pollutant loadings.</FONT></P>
Dave R. HendersonG. Dennis PipkinJuly 2002 - December 2003
102
Complete
1
2004-06
65
  
861182003EnvironmentWetlands MitigationEcological Assessment of a Wetlands Mitigation Bank (Phase III : Restoration Efforts)
<P><FONT face=Verdana size=2>Assessing the success of wetland restoration projects requires an evaluation of ecosystem structure and function. Long-term success is rarely documented, and failure is common for a variety of reasons. Our overall goal is to continue to evaluate the ecological success of the Tulula Wetlands Mitigation Bank in response to restored hydrology, soils, and vegetation. Our data will provide NCDOT an ecological assessment that will be useful for evaluating other wetland restoration projects throughout the state. </FONT></P><br><P><FONT face=Verdana size=2>The following objectives provide the framework for a comprehensive ecological assessment of the restored wetlands of Tulula:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>determine the success of stream realignment by evaluating the geomorphology of the new channel before and after water is introduced,</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>evaluate changes in ecosystem structure and function (including soil and decomposition processes) associated with plant community succession in planted and unplanted portions of the floodplain in response to a higher water table and overbank flooding, and</FONT> </FONT><br><LI><FONT size=2><FONT face=Verdana>evaluate wildlife use of the site in response to changing hydrologic conditions (amphibians) and plant community succession (birds).</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>Significant progress was made on restoring the wetlands at Tulula in 2001. Water is now flowing in four of five constructed meandering stream sections, and the dredged Tulula Creek has been filled in those sections. The golf ponds built for the abandoned golf course were partially refilled using spoil generated during their construction, and the floodplain was recontoured in the constructed channel/golf pond areas to enhance heterogeneity in topography (thereby increasing the heterogeneity of wetlands). Site restoration will be finished in 2002 when the fifth and final constructed stream section is connected and the disturbed areas of the floodplain are planted with hardwood trees. </FONT></P><br><P><FONT face=Verdana size=2>This project will contribute to the long-term analysis of site ecology, and provide information that will guide NCDOT and other government agencies involved with wetland mitigation projects throughout North Carolina.</FONT></P>
Gordon CashinG. Dennis PipkinJuly 2002 - June 2004
102
Complete
1
2004-09
66
  
881192003EnvironmentWater Quality and Pollutant DischargeEvaluation and Implementation of BMPs for NCDOT's Highways and Industrial Facilities
<P><FONT face=Verdana size=2>This research project will support North Carolina Department of Transportation's (NCDOT) on-going activities pertaining to the implementation of best management practices (BMPs) on NCDOT maintained highway and industrial facilities. </FONT></P><BR><br><P><FONT face=Verdana size=2>Under the provisions of the National Pollutant Discharge Elimination System (NPDES), NCDOT is required to perform the evaluation of BMP effectiveness from industrial facilities and highway sites owned by NCDOT. These consist of installing new and/or retrofitting existing BMP's for all fourteen (14) divisions and at numerous industrial facility sites.</FONT></P><BR><br><P><FONT face=Verdana size=2>As of this date, NCDOT has performed industrial monitoring programs for a stormwater wetland in Wilson County; dry detention basin at Alexander County's maintenance yard; and an inlet control, erosion control and housekeeping, and gravel pad in Orange County. Numerous highway retrofit options are being reviewed including: water quality swale, bioretention, pocket wetland, stormwater wetland, extended dry detention basin, grade control structure with grass swale, water quality hazard spill basin, level spreader with forested/vegetated filter strip and grass swale with curb cut. The overall effort for BMP assessments requires an enormous undertaking and collaboration of engineering design, installation, field monitoring, synthesis of literature information, analysis of monitoring data, and assessment of BMP performance and effectiveness.</FONT></P><BR><br><P><FONT face=Verdana size=2>NCDOT is currently assisted by NCSU in field monitoring and runoff sample collection (typically from influent and effluent of a monitoring site), and by others in BMP design and drawing. Researchers from UNC-Charlotte thereby propose to provide evaluation and technical assistance for the on-going BMP implementation activities pertaining to equipment wash/maintenance facilities and highway BMP monitoring sites. Four main objectives of this project are described below.</FONT></P><BR><br><OL><BR><br><LI><FONT size=2><FONT face=Verdana>For the equipment wash/maintenance facilities, we will (a) identify existing procedures and practices for equipment washing activities at NCDOT; (b) perform review of existing state-of-the art practices at other states; (c) quantify pollutants of concern in equipment-wash wastewater by performing on site sample collection; and (d) identify effective alternatives to equipment washing for NCDOT operations.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>For BMP activities, we will (a) provide technical management and support to coordinate BMP research project activities; and (b) assist NCDOT in site selection of monitored BMP sites and final report preparation.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>We will perform systematic evaluation and tracking of monitored and non-monitored industrial and highway sites (9 monitored, 3 non-monitored). Variables to monitor include: aesthetics, costs, design criteria, effectiveness, efficiency, innovation, level of service, nutrient management, pollutant removal, remediation requirements, and site constraints.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>We will also develop a GIS-database for all BMP monitored and non-monitored sites.</FONT> </FONT></LI></OL>
Matt S. LaufferG. Dennis PipkinJuly 2002 - December 2004
102
Complete
1
2006-02
67
  
901042004Pavement & MaintenanceAsphalt Mix DesignOptimizing Gradations for Surface Treatments
<P><FONT face=Verdana size=2>Asphalt surface treatments are among the most efficient and cost-effective methods utilized by state highway agencies to preserve and rejuvenate existing pavements. Specific benefits of using surface treatments include sealing pavements against water and air, restoring weathered and raveled surfaces, and providing skid-resistant surfaces, to name a few. However, the economic advantages of surface treatments may easily be forfeited through faulty design or poor mixture characteristics. Although many design methods exist, most state agencies still rely on experience and/or precedent in designing their mixtures, a practice that often results in surface treatments with poor performance.</FONT></P><BR><br><P><FONT face=Verdana size=2>Due to the ongoing commitment to pavement preservation and the growing number of miles of low volume roads, the use of surface treatments has increased substantially in recent years and is likely to continue to rise in the future. This increase in the use of surface treatments has led state agencies to invest in reviewing their design procedures and to modify their existing specifications and develop new mix design systems. Such systems would address material selection, mixture characteristics, performance evaluation, and other influencing factors such as traffic, climate, and existing pavement conditions.</FONT></P><BR><br><P><FONT face=Verdana size=2>The primary objectives of the proposed research are:</FONT></P><BR><br><OL><BR><br><LI><FONT size=2><FONT face=Verdana>to obtain material properties, particularly aggregate gradation, and mix design guidelines for typical surface treatments in North Carolina as well as other states;</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>to determine particular mix characteristics and performance criteria related to aggregate retention, bleeding, and skid resistance;</FONT> </FONT><BR><br><LI><FONT face=Verdana size=2>to study the effects of aggregate gradation and other mix characteristics on performance and evaluate life cycle costs; and </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>to propose guidelines for the design of new mixtures and/or modifications of existing specifications.</FONT> </FONT></LI></OL><BR><br><P><FONT face=Verdana size=2>The developed guidelines and recommended modifications to the existing specifications will provide the NCDOT with a tool to improve performance of surface treatments. This provision may be in the form of improved operational efficiency, longer service life, and improved ride quality, which together would lower life cycle costs and increase safety and customer satisfaction.</FONT></P>
Judith Corley-LayMustan KadibhaiJuly 2003 - June 2005
102
Complete
1
2005-15
68
  
921052004Pavement & MaintenancePavement PerformanceQuantifying Anti-Strip Additive in Asphalt (Binder & Mixes)
<P><FONT face=Verdana size=2>NCDOT requires anti-strip agent in all asphalt mixes. To date, there is no test procedure to determine the level of organic anti-strip agents in asphalt binders or asphalt mixtures. A reliable standardized test procedure will allow NCDOT to determine if the specified level of organic anti-strip agent has been added to the mix and hence, reduce the amount of substandard asphalt mix being placed in the field. It will also allow NCDOT and asphalt manufacturers to have a quality control test to inspect asphalt binders and hot mix samples. <BR><BR></FONT><FONT face=Verdana size=2>The objective of this research will be to develop a reliable and repeatable laboratory and/or field test procedure to determine the amount of organic anti-strip agent in asphalt binders and asphalt mixtures. In this investigation, two test methodologies will be investigated. These include 1) a colorimetric test, and 2) a litmus test using the StripScan device. Both methodologies utilize a spectrophotometer for the analysis of anti-strip additive concentration in asphalt mixes.<BR><BR></FONT><FONT face=Verdana size=2>The anticipated research product will include a reliable test procedure that can be used by NCDOT as well as asphalt manufacturers for quality control testing to inspect asphalt binders and hot mix samples to determine if the specified level of anti-strip agent has been added to the mix.</FONT></P>
Jack CowsertMustan KadibhaiJuly 2003 - December 2004
102
Complete
1
2005-16
69
  
941062004Pavement & MaintenanceConcrete PavementsEvaluation of Acceptance Strength Tests for Concrete Pavements
<P><FONT face=Verdana size=2>The main purpose of the proposed research is to evaluate the feasibility of using other<BR>tests for acceptance testing of concrete pavements. Specifically, it is proposed to implement a laboratory research project to prepare specimens for bending beam tests, compressive strength tests, and split tension tests; furthermore, it is proposed to perform non-destructive free-free resonant column tests on every specimen prepared for the strength tests. The specimens will be prepared, cured, and tested in a laboratory setting. The results of the tests will be used to correlate the modulus of rupture obtained in the bending beam tests to the compressive strength measured on concrete cylinders, the tensile strength measured in the split tension tests, and to the low-strain dynamic modulus measured in the resonant column tests.</FONT></P>
Judith Corley-LayMustan KadibhaiJuly 2003 - December 2004
102
Complete
1
2006-10
70
  
961072004EnvironmentFlora and FaunaNew Hope Creek Bridge as a Wildlife Underpass
<P><FONT face=Verdana size=2>There are numerous concerns regarding impacts of highway bridge construction on wildlife and wildlife habitat. Some concerns focus especially on wildlife mortality or, since the area surrounding the project has one of the highest recorded deer-vehicle accident rates in North Carolina, the potential for human injury in deer-vehicle collisions. Hence, the construction footprint and duration, and post-construction configuration relative to adjacent wildlife habitat are issues that require study and documentation. Furthermore, highways may fragment wildlife habitat, which leads to diminished habitat quality, and reduced survival and reproduction of wildlife species.</FONT></P><br><P><FONT face=Verdana size=2>The objectives of this research project are to:</FONT><BR></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Determine impacts of US 15-501 bridge construction across New Hope Creek on white-tailed deer movements, survival and habitat use.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Evaluate deer use of existing landscape configuration in the context of corridors, habitat fragmentation and potential for vehicular interactions.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Compare deer movement and activities within "similar areas" of nearby bridges?</FONT> </FONT><BR><br><LI><FONT face=Verdana><FONT size=2>Compare deer movement and activities with a "similar area" not impacted by construction</FONT>.</FONT> </LI></OL>
Gordon CashinG. Dennis PipkinJuly 2003 - June 2005
102
Complete
1
2005-11
71
  
981082004EnvironmentFlora and FaunaA Comparison of the Impacts of Culverts Versus Bridges on Stream Habitat and Aquatic Fauna
<P><FONT face=Verdana size=2>Freshwater mussels that inhabit surface waters in North Carolina are among the most endangered animals on the planet. More than 80% of the State's freshwater mussel species are imperiled. Strong, healthy mussel populations are an indicator of good water quality. Mussels also help to improve water quality by their natural filtering system.<BR><BR></FONT><FONT face=Verdana size=2>The construction of crossing structures to support new roads is an essential component of rural economic development but bridges and culverts can adversely alter stream habitat. When roads cross streams, natural resource managers recommend the use of a bridge rather than a culvert, because it is perceived that culverts do more damage to stream habitat. However, culverts are more cost-effective because they are often less expensive to install, require less maintenance, and have longer effective life. We propose research to help resolve this contentious issue. The proposed effort builds on the results of two previous NCDOT supported studies and focuses on measuring and comparing the impact of culverts and bridges on freshwater mussels and aquatic habitat. <BR><BR></FONT><FONT face=Verdana size=2>The primary goal of the proposed research is to compare the impact of culverts and bridges of various designs on freshwater mussel populations.<BR><BR></FONT><FONT face=Verdana size=2>Specific objectives of the proposal include:</FONT><BR></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Determining the impact of culverts on the relative abundance, diversity and spatial distribution of freshwater mussels in North Carolina piedmont;</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Measuring essential habitat characteristics to determine the physical impact of culverts;</FONT> </FONT><BR><br><LI><FONT face=Verdana size=2>Comparing newly acquired data to existing data gained in previous surveys of 69 bridges and 11 culverts of various designs, and </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Identifying crossing structure design attributes that may alter the physical or biological impact on streams.</FONT> </FONT></LI></OL>
Gordon CashinMrinmay "Moy" BiswasJuly 2003 - June 2005
102
Complete
1
2006-15
72
  
1001092004EnvironmentFlora and FaunaAn Evaluation of Hemolymph Extraction as a Non-Lethal Sampling Method for Genetic Identification of Freshwater Mussel Species in Southeastern North Carolina
<P><FONT face=Verdana size=2>State and federal regulatory agencies increasingly call upon NCDOT biologists to determine whether the site for a proposed construction project is HOME to an endangered or threatened species of freshwater mussel. Biologists conducting surveys currently depend on species identification based primarily on examination of diagnostic shell characteristics, which are difficult to discern and may be unreliable, even in the hands of experts. Genetic identification offers a powerful alternative, but creates new challenges that this proposal aims to help solve. First, we will overcome the need to sacrifice animals or to obtain tissue biopsies, neither of which is a viable approach to sampling a threatened population. The methods we develop for obtaining, storing, and processing hemolymph for DNA extraction will allow even the rarest species to be sampled with little or no risk of mortality. Secondly, genetic methods based on DNA sequence analysis require equipment and expertise not generally available to NCDOT and other state agencies. However, the end result of our work will be standard operating procedures that will involve DNA extraction, Polymerase Chain Reaction, restriction digestion, and agarose gel electrophoresis that will greatly simplify genetic analysis as well as establish a standard set of procedures that will ensure consistency across the state. Standardization of identification procedures will streamline the process, and each additional analysis, if added to a common database, will further our ability to quickly evaluate the genetic distinctiveness of mussel populations. Such methodologies could substantially facilitate the evaluation process of potential impacts from proposed NCDOT construction projects.<BR><BR></FONT><FONT face=Verdana size=2>The objectives of this research project are:</FONT></P><br><OL><br><LI><FONT face=Verdana size=2>To obtain hemolymph samples from several freshwater mussel individuals from several species collected at multiple sites in Lake Waccamaw. </FONT><BR><br><LI><FONT face=Verdana size=2>To monitor the survivorship of sampled individuals for several weeks to evaluate the effects of hemolymph withdrawal on survivorship under field conditions. </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To develop methods for hemolymph transport, storage and processing to allow extraction of PCR-amplifiable DNA from this tissue.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To PCR amplify and sequence the DNA of 2 mtDNA regions and 1 nuclear DNA region from a subset of the individuals sampled.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To analyze the DNA sequences phylogenetically to define monophyletic groups (i.e. species and subspecies), and to use these analyses to design genus- and species-specific restriction endonuclease digestion assays.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To apply methods developed in (5) to new locations, we will sample and sequence the DNA, then perform diagnostic restriction digests on selected animals from adjacent and more distant collection sites in North Carolina.</FONT> </FONT></LI></OL>
Gordon CashinMustan KadibhaiJuly 2003 - June 2005
102
Complete
1
2006-11
73
  
1021102004PlanningPublic & Rural TransportationUse of Performance Measures and Standards for Public Transportation Systems
<P><FONT face=Verdana size=2>There is a need for consistent standards against which to measure the performance of North Carolina public transportation system operators. Therefore, this research study addresses two primary questions: 1) What are appropriate performance measures to use? 2) Should performance measures be used to determine the allocation of funding, and if so, in what way?</FONT></P><br><P><FONT face=Verdana size=2>To be effective, performance measures must reflect state and local goals, respond to the variety of types and sizes of public transportation systems, address the multitude of services operated, account for constraints outside the control of the transit system, and accommodate differing local needs and conditions. </FONT></P><br><P><FONT face=Verdana size=2>The second question, "Should performance measures be used to determine the allocation of funding, and if so, in what way?" has at least two important sub-questions that are addressed by the study: 1) If performance measures are used to determine funding allocations, should that be for all or just part of a system's funding? If part, what part? 2) How can the potential conflict between funding need and system performance be resolved? Often a system with the most urgent need for funds is also a system that is performing poorly.</FONT></P>
Miriam PerryMrinmay "Moy" BiswasJuly 2003 - June 2004
102
Complete
1
2004-10
74
  
1041112004PlanningTraffic Surveys, Modeling and ForecastingNorth Carolina Forecasts for Truck Traffic
<P><FONT face=Verdana size=2>The project goal is to improve truck traffic forecasts. The approach relies on improved truck traffic data collection, analytical methods tempered by expert judgment, and graphical methods in easy-to-visualize formats that allow integration of multiple factors that affect truck traffic. Standard trend lines can be enhanced by comparative graphics for truck traffic growth on similar facilities in similar urban or rural locations. Besides traditional statistical graphics, GIS graphical techniques keyed to network geography and the developing linear referencing system at NCDOT may prove very useful. GIS databases will also allow direct visual comparison of truck traffic trends to expected population and economic growth in the study area. Thus, an experienced traffic forecaster will be able to compare truck forecasts versus other indicators for growth in the study area. <BR><BR></FONT><FONT face=Verdana size=2>The scope of the project will be limited to areas and highway facilities within North Carolina. Variables to consider are locations within the state such as eastern, mid and western study areas, highway facilities such as interstate, intrastate, primary and secondary routes. Special locations including bridges and paving projects may be considered depending on the interests of NCDOT pending discussion of project scope. Urban and rural locations with relatively static or dynamic "suburban ring" growth may be considered, as will be locations proximate to truck generators. The study is undertaken with the understanding that all traffic forecasts are uncertain and that the longer the forecast period, the more uncertain the forecast. Yet, uncertainty will not explicitly be considered in the forecasts. Rather, it is hoped that comparative past and future economic development and highway improvement scenarios can be indicated to help the forecaster judge the relative likelihood of alternative forecasts.<BR><BR></FONT><FONT face=Verdana size=2>The specific objectives of the proposed research are:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>To assess NC truck traffic as functions of facility type, geographic region and other factors.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To develop a methodology and tools for evaluating truck traffic trends.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To use graphical tools to compare and enhance truck forecasts using other growth indicators such as population and economic development.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>To demonstrate truck traffic forecasting methods with one or more case studies.</FONT> </FONT></LI></UL>
Joseph N. SpringerMrinmay "Moy" BiswasJuly 2003 - December 2004
102
Complete
1
2006-28
75
  
1061122004Structures & ConstructionDurability and Corrosion ResistanceConcrete Diffusion Coefficients and Existing Chloride Exposure in North Carolina
<P><FONT face=Verdana size=2>During this project, an investigation will be performed to determine a correlation between the Rapid Chloride Permeability Test (RCPT) results and the diffusion coefficients of the same concrete samples. This correlation will be performed on 15 concrete mix designs specified by the NCDOT engineers. The results of this work will support a mathematical model to be used in predicting the service life of bridges across North Carolina. The project will also include the evaluation of core samples taken from 25 reinforced concrete bridges located in various geographical locations. The data generated in this phase will provide comprehensive chloride profiles and chloride loading data for regions of North Carolina and for typical bridge structural components.</FONT></P><br><P><FONT face=Verdana size=2>Among these 25 bridges, special attention will be given to the US264 structure over the Croatan Sound (Manteo Bypass), by performing a thorough analysis of the RCPT values obtained throughout the structure.</FONT></P>
Greg PerfettiMrinmay "Moy" BiswasJuly 2003 - June 2005
102
Complete
1
2006-26
76
  
1081132004Structures & ConstructionBridge DesignReview of NCDOT Practices for Analyzing Overhang Falsework
<P><FONT face=Verdana size=2>An effort by NCDOT to produce standardized details for bridge overhang falsework<BR>has identified a need to review the current analysis and design procedures adopted by the department. The review is necessary to ensure that the analysis procedures and the design assumptions integrated into the current guidelines are not too restrictive and that they are in compliance with the latest ACI and AASHTO specifications. </FONT></P><BR><br><P><FONT face=Verdana size=2>The primary objectives of the proposed research are to provide a comprehensive review of the current procedures used by the NCDOT to analyze bridge deck overhang falsework and to evaluate the appropriateness of the NCDOT design assumptions. Comments and recommendations for improvement and modification of the current analysis and design procedures will be provided.</FONT></P><BR><br><P><FONT face=Verdana size=2>The proposed research will provide a direct benefit in construction cost savings and submittal review time required by NCDOT personnel. It will also improve safety on the construction site.</FONT></P>
Greg PerfettiMrinmay "Moy" BiswasJuly 2003 - June 2004
102
Complete
1
2006-22
77
  
1101142004Structures & ConstructionBridge DesignDevelopment of a Simplified Procedure to Predict Dead Load Deflections of Skewed and Non-Skewed Steel Plate Girder Bridges
<P><FONT face=Verdana size=2>Many of today's bridge construction projects are erected in stages to limit traffic interruptions or to minimize the environmental impacts. Typically, one half of the bridge superstructure is constructed in the first stage and the other half constructed in the second stage. The final stage is to cast a closure pour to join the deck slabs of the two structures together. </FONT></P><br><P><FONT face=Verdana size=2>Matching the final deck elevations of the first two stages of construction has created numerous problems during construction. Most common are construction delays caused by the need to reanalyze the structure and reset the screed and buildup elevations. Improperly aligned deck elevations between the two stages may require the need for grinding of the deck surface after placing the closure pour. In addition, reduction of the thickness of the deck may result in reduction of the concrete cover leading to possible deterioration of the bridge deck. The misalignment of the two deck slab surfaces may occur due to differential non-composite deflections of the adjacent girders in different stages of construction. </FONT></P><br><P><FONT face=Verdana size=2>Deflection calculations are normally based on a single girder line with no accommodation for the varying transverse distribution of the loads. The variation in the transverse load distribution occurs because of frame action exhibited by the cross-frames connecting the girder lines, the effects of bridge skew, and variations in non-composite dead load due to different overhang conditions. </FONT></P><br><P><FONT face=Verdana size=2>The solution to this problem is to create a three-dimensional finite element computer model that is more accurately representative of the three-dimensional behavior of the structure. Creation of the computer models is a very time consuming task that must be performed by an engineer with considerable experience in computer modeling. This represents an extremely laborious task for the NCDOT to perform on all staged-construction projects.</FONT></P><br><P><FONT face=Verdana size=2>The primary objective of this research is to develop an empirically based method to predict the non-composite deflection of steel plate girders in staged-constructed bridges. The effects of bridge skew, girder length, girder spacing, cross-frame stiffness, in-place deck slab thickness, and composite action on a portion of the girder length will be included in the method. Simple span, two span continuous, and three span continuous bridge configurations will be considered. The empirically based method will utilize a series of simple modifiers to adjust the traditionally predicted single girder line deflection to the expected staged-construction deflection. The formulation of the simplified method will require a combination of field-measured data and extensive three-dimensional analytical simulation.</FONT></P><br><P><FONT face=Verdana size=2>The research will provide a direct benefit in cost savings to the NCDOT both in the long-term and short-term. These benefits will be realized by decreasing construction delays and design time required to predict the deflection during staged construction of the girders. In addition, the possible deterioration of the bridge deck and the needs for repairs due to insufficient concrete cover of the reinforcement will be eliminated.</FONT></P>
Ron HancockMrinmay "Moy" BiswasJuly 2003 - June 2005
102
Complete
1
2006-13
78
  
1121152004Structures & ConstructionComposite & Innovative MaterialsValue Engineering and Cost Effectiveness of Various Fiber Reinforced Polymer (FRP) Repair Systems
<P><FONT face=Verdana size=2>The proposed research program is designed to investigate the feasibility of using the<BR>most efficient externally bonded FRP repair/strengthening system to rehabilitate AASHTO prestressed concrete bridge girders damaged due to accident or collision impact causing loss of prestressing and/or spalling of concrete. The research will be conducted on AASHTO Type II girder from Bridge No. 169 in Robeson County in the State of North Carolina. The proposed project will investigate the efficiency and cost-effectiveness of externally bonded FRP sheet and strip repair/strengthening systems using prestressed channel beams to be supplied by NCDOT from existing bridges. The Maintenance Department also recommended to extend the investigation to include Near-Surface-Mounted (NSM) FRP bars and strips for the prestressed channel beams. The NSM system is envisioned to be a valuable system for these type of applications. The research consists of an experimental program to examine the flexural behavior under the effect of static and fatigue loadings that closely simulate field conditions.</FONT></P>
Lin WigginsMrinmay "Moy" BiswasJuly 2003 - June 2005
102
Complete
1
2006-27
79
  
1122162004Traffic & SafetyITS and Incident ManagementI-40 Lane Reversal Traffic Analysis
<P><FONT face=Verdana size=2>Following the unprecedented multi-state coastal evacuation for Hurricane Floyd in 1999, the NCDOT developed a lane reversal plan for I-40 to facilitate the safe and efficient evacuation of residents and tourists in southeastern North Carolina. The plan, approved in 2000, was developed and will be administered by the NCDOT in concert with the Department of Crime Control and Public Safety - Division of Emergency Management and State Highway Patrol. The reversal plan is detailed and thorough. However, an in-depth traffic operations analysis has not been performed for the plan, and the NCDOT has specific concerns about the plan operation.</FONT></P><br><P><FONT face=Verdana size=2>The proposed two-year project will address these concerns. The first year will include a review of relevant literature; review and assessment of evacuation experiences in NC and other states; data assessment, collection and assembly; model scoping and selection of modeling tools; and development of evacuation scenarios. Given the critical need to assess the operational characteristics at the beginning of the reversal, the first year will also include focused modeling of the transition to contraflow and presentation of the preliminary findings from this modeling effort.</FONT></P><br><P><FONT face=Verdana size=2>The second year will include modeling of the entire lane reversal plan, presentation of interim findings, incorporation of NCDOT feedback into final model runs, and preparation of the project final report. Based on the NCDOT feedback and direction, the final modeling phase will likely involve assessment of possible changes to the current lane reversal plan.</FONT></P>
Kelly DamronMustan KadibhaiJuly 2003 - June 2005
102
Complete
1
2005-14
80
  
1141172004Traffic & SafetyTraffic SafetyReasonable Speeds on Improved Curb and Gutter Facilities
<P><FONT face=Verdana size=2>The NCDOT spends hundreds of millions of dollars each year widening old two-lane roads with 55 mph speed limits into multilane highways. Sometimes on those multilane highways the Department has to construct vertical curbs for access control or other reasons. Since there is clear and well-known guidance that vertical curbs should not be placed next to high-speed lanes, the NCDOT typically uses a lower design speed (50 mph) and posted speed limit (usually 45 mph) on such segments. This lower speed limit creates an enforcement problem, as drivers do not perceive danger from the curbs and try to travel at least as fast as they did before the road was improved.</FONT></P><br><P><FONT face=Verdana size=2>The NCDOT needs better information to avoid the scenario described above. Specifically, the NCDOT needs answers to two key questions:</FONT></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Do vertical curbs next to high-speed lanes really cause more frequent and severe collisions than other cross-section choices? The crash test research is clear, but evidence from collision data is much less convincing.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>If vertical curbs are more dangerous, is a lower speed limit the best way to alert the public to this danger or are there other treatments that the NCDOT should use?</FONT> </FONT></LI></OL><br><P><FONT face=Verdana size=2>The purpose of this research is to answer those questions for North Carolina roadways. With answers to those questions, the NCDOT can avoid the scenario described above.</FONT></P><br><P><FONT face=Verdana size=2>The main effort in this research will be to find a sample of higher-speed roads with vertical curbs with 45 mph and 55 mph speed limits and examine the collision records and vehicle speed distributions on those roads. The primary research product will be a summary report documenting the answers to the questions and any recommendations based on those answers. The summary report will serve the NCDOT as a technical reference when designing roads with vertical curbs and establishing speed limits on such roads. The report should also be circulated to the State Highway Patrol and other police agencies that enforce those speed limits.</FONT></P>
A. D. (Tony) WyattMustan KadibhaiJuly 2003 - December 2004
102
Complete
1
2005-12
81
  
1161182004EnvironmentWater Quality and Pollutant DischargeOperational Evaluation of Emissions and Fuel Use of B20 vs. Diesel Fueled Dump Trucks
<P><FONT face=Verdana size=2>NCDOT is proceeding with the use of alternative fueled vehicles (AFVs), including biodiesel-fueled medium duty trucks. Diesel vehicles contribute substantially to statewide emissions of NOx, an ozone precursor, and to particulate matter. There is a need for empirical quantification and comparison of emissions, fuel economy, and vehicle operation on both conventional and biodiesel fuels.</FONT></P><br><P><FONT face=Verdana size=2>This project addresses these critical needs based upon four tasks. Task 1 involves design of field data collection study to measure second-by-second emissions of NOx, particulate matter, CO, and CO2, fuel use engine data and vehicle activity (e.g., speed, location) data using an on-board portable instrument. Task 2 involves the field data collection itself, including the logistics of instrument calibration and deployment. Task 3 involves data reduction and analysis for the purpose of developing benchmark modal emission rates that enable comparison of B20 and conventional diesel fuel. Task 4 involves the development of strategic recommendations based upon empirical data collected in the study in order to address the key needs of NCDOT, including evaluation of the benefits of biodiesel fuel, air quality management, energy management, and improved operation. </FONT></P><br><P><FONT face=Verdana size=2>The primary product of this work will be a database, analysis and recommendations pertaining to operational practices and their implications for fuel use and emissions. The data will be based upon real-world, on-road in-use measurements of fuel economy and emissions on a second-by second basis. A secondary product of this work will be information and data that can be used to assess compliance of North Carolina with respect to the National Ambient Air Quality Standards and conformity. Another secondary benefit of this work could be realized based upon transfer of the emissions data to other agencies to support more realistic and scientifically defensible estimates of emissions pertaining to North Carolina. This, in turn, would support more appropriate air quality and energy policy strategies.</FONT></P>
G. Dennis PipkinOctober 2003 - September 2004
102
Complete
1
2005-07
82
  
421192004EnvironmentWetlands MitigationMethodology to Assess Soil, Hydrologic, and Site Parameters that Affect Wetland Restoration-Phase II
<P><FONT face=Verdana size=2>This project is a continuation of the research conducted under Research Project 2001-09, "Methodology to Assess Soil Hydrologic &amp; Site Parameters that Affect Wetland Restoration Success". The overall goal of the research is to evaluate the strategy and performance of the restoration of wetland functions in Juniper Bay and to test alternative restoration methods. Restoration efforts will include filling in drainage ditches as necessary to restore historical hydrologic functions, re-establishing the forest community in accordance with community types and providing soil management as needed to assist in hydrologic function restoration. This project is significant because it will help to assist the NCDOT in permit acquisition and help to improve effective restoration techniques of wetlands.</FONT></P>
Jim HauserG. Dennis PipkinJuly 2003 - June 2006
101
In Progress
1
2006-47
83
  
1181232004EnvironmentWater Quality and Pollutant DischargeMonitoring the Effects of Highway Construction Over the Little River and Crane Creek
<P><FONT face=Verdana size=2>The objectives of this study are to:</FONT></P><BR><br><OL><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Document the changes in the water quality of Crane Creek and the Little River associated with NCDOT's construction of Highway 1.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Evaluate the monitoring data to determine if changes in water quality parameters are significant.</FONT> </FONT></LI></OL>
Ted SherrodG. Dennis PipkinJuly 2003 - June 2005
102
Complete
1
2005-10
84
  
1201252004Structures & ConstructionBridge DesignImplementation of Self-Consolidating Concrete for Prestressed Concrete Girders
<P><FONT face=Verdana size=2>Research is needed to monitor the performance of SCC in a field production environment and to assess the behavior of prestressed SCC girders in order to obtain more research data from the field and to demonstrate the proper application of this new materials technology.</FONT></P><BR><br><P><FONT face=Verdana size=2>The objectives of this research are three-fold: (1) Determine and document the various properties of SCC used in the production of two prestressed SCC girders. (2) Monitor and document the actual production of two prestressed concrete girders using SCC. The girders will be selected from a NCDOT bridge project under contract. (3) Conduct static load tests of two SCC girders and one non-SCC girder at the production site. The girders will be tested to full service load condition in order to validate their design and performance. Subject to satisfactory performance, the girders may be delivered and installed in the bridge for service as other non-SCC girders.</FONT></P>
Greg PerfettiMrinmay "Moy" BiswasNovember 2003 - June 2004
102
Complete
1
2006-30
85
  
1202262004EnvironmentErosion and Turbidity ControlMonitoring the Effects of Highway Construction in the Sedgefield Lakes Watershed
<P><FONT face=Verdana size=2>Currently under the North Carolina Sedimentation Control Commission rules, runoff leaving a construction site must meet a clarity or turbidity standard of £ 50 NTU or the site must have proper and approved best management practices (BMP's) installed and maintained. Sediment from construction sites received public notoriety in North Carolina in 1997 when a plume of red, muddy runoff, thought to be from construction sites, was photographed on its way down the Neuse River. Following this incident, the Governor called on the NC Department of Environment and Natural Resources (NC DENR) to begin stricter enforcement of erosion and sediment control regulations on construction sites. The muddy plume incident and increased public scrutiny has resulted in the need for reliable and defensible documentation of the effectiveness of erosion and sediment control efforts.</FONT></P><br><P><FONT face=Verdana size=2>One of the most defensible ways to demonstrate the effectiveness of erosion and sediment control programs is through water quality monitoring of surface water resources in close proximity to the construction. The following proposal outlines the monitoring plan for the Sedgefield Lakes watershed in Guilford County, NC.</FONT></P><br><P><FONT face=Verdana size=2>The objectives of this study are to:</FONT></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Document the changes in the water quality of unnamed tributaries to Sedgefield Lakes as a result of highway construction in the watershed.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Evaluate the monitoring data to determine if changes in water quality parameters are significant.</FONT> </FONT></LI></OL>
Ted SherrodG. Dennis PipkinDecember 2003 - December 2005
102
Complete
1
2006-07
86
  
1203052005EnvironmentStream MitigationEvaluating Systems to Reduce Road Improvement Impacts on Mountain Streams
<P><FONT face=Verdana size=2>Erosion and sediment control on construction sites is an increasingly important aspect of project management. Most erosion control practices which are currently implemented as part of a sediment and erosion control plan are intended to prevent erosion through diversions, mulching, and seeding. Sediment control is designed to slow runoff to allow entrained soil to settle. However, projects located adjacent to streams with minimal buffers are particularly challenged because there is little land available to construct traditional controls such as sediment traps and basins. This is further exacerbated by the steeper slopes found along many mountain streams. These are particularly valued for their water quality and stream habitat, which can both be impacted by disturbances in the watershed. This combination may be effective in retaining a large portion of potential sediment within the construction site, but runoff is likely to remain highly turbid. The suspended solids concentration in the discharge water has adverse impacts on the receiving waters and may result in complaints from the public.</FONT></P><BR><br><P><FONT face=Verdana size=2>Over the course of the project, we will establish monitoring of erosion and sediment control at three sites where road improvements are being implemented. We will attempt to find sites widely distributed in the mountain region. At each site, we will:</FONT><BR></P><br><OL><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Conduct detailed monitoring of erosion and sediment control effectiveness under typical and modified systems on road improvement projects adjacent to mountain streams.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Compare a variety of erosion control systems for effectiveness, including combinations of standard straw, polyacrylamide, rolled erosion control products, composts, and manufactured matrix hydromulching.</FONT> </FONT><BR><br><LI style="FONT-SIZE: x-small; FONT-FAMILY: "><FONT size=2><FONT face=Verdana>Install, evaluate, and improve (as needed) systems to increase sediment and turbidity control in standard and modified ditches, traps and basins.</FONT> </FONT></LI></OL>
Ted SherrodG. Dennis PipkinJuly 2004 - June 2005
102
Complete
1
2006-44
87
  
1221062005EnvironmentWetlands MitigationEcological Assessment of a Wetlands Mitigation Bank (Phase IV: Post-Restoration)
<P><FONT face=Verdana size=2>Compensatory mitigation for wetland loss was established in the United States to help achieve a national goal of no-net-loss of wetlands (Marsh et al. 1996). The effectiveness of this policy has come under scrutiny because of significant failure rates of projects and the difficulty of assessing long-term success within the 3-5 year post-restoration window that is set by most regulatory agencies (Mitsch and Wilson 1996, Zedler 1996, Whigham 1999, Brown and Veneman 2001, National Resource Council 2001). Assessing the success of wetland restoration projects requires an evaluation of ecosystem structure and function. Researchers primarily have assessed restoration success using hydrology and vegetation, with the assumption that functional success will occur if structural components are successfully restored. Long-term success is rarely documented, and failure is common for a variety of reasons. Our overall goal is to continue to evaluate the ecological success of the Tulula Wetlands Mitigation Bank in response to restored hydrology, soils, and vegetation. Our data will provide NCDOT an ecological assessment that will be useful for evaluating other wetland restoration projects throughout the state.<BR><BR></FONT><FONT face=Verdana size=2>The following objectives provide the framework for a comprehensive ecological assessment of the restored wetlands of Tulula: 1) determine the success of stream realignment by evaluating the geomorphology of the restored channel, 2) evaluate changes in ecosystem structure and function (including soil processes) associated with plant community succession in planted and unplanted portions of the floodplain in response to a higher water table and overbank flooding, and 3) evaluate wildlife use of the site in response to changing hydrologic conditions (amphibians) and plant community succession (birds).<BR><BR></FONT><FONT face=Verdana size=2>Significant progress was made on restoration at Tulula in 2001 and 2002. Water is now flowing in the restored stream channel. The golf ponds built for the abandoned golf course were partially refilled, and the floodplain was re-contoured in the constructed channel/golf pond areas to enhance heterogeneity in topography (thereby increasing the heterogeneity of wetlands). Tree saplings were planted in the re-contoured floodplain. UNCA has established a variety of ecological studies in the restored portions of Tulula, and data from these studies will be combined with other studies to determine how the site responds to restoration.<BR><BR></FONT><FONT face=Verdana size=2>UNCA has established long-term monitoring sites throughout the Tulula Wetlands Mitigation Bank. We have ecological data that spans almost ten years and which will provide an excellent framework for evaluating restoration efforts. The ecological research done by UNCA has significantly influenced restoration strategies for the site. Our continuing efforts will provide NCDOT with the most comprehensive database on wetlands restoration in North Carolina. Past CTE and NCDOT funding for this project have allowed UNCA to provide research opportunities for over 60 undergraduate students. </FONT><FONT size=2><FONT face=Verdana><BR><BR>We have outlined projects in this proposal that continue past research efforts as well as initiate new efforts to expand our assessment of restored wetlands at Tulula. The proposed projects will contribute to the long-term analysis of site ecology, and provide information that will guide NCDOT and other government agencies involved with wetland mitigation projects throughout North Carolina. </FONT><BR></FONT></P>
Mike SandersonG. Dennis PipkinJuly 2004 - June 2006
102
Complete
1
2006-16
88
  
1241072005EnvironmentFlora and FaunaPropogation of Freshwater Mussels for Release into North Carolina Waters
<FONT face="Times New Roman" size=2><br><P align=left>Propagation and culture of freshwater mussels has been identified as important to their conservation. Though some propagation had been done previously in North Carolina, it was done on a small scale and for experimental purposes only. The purpose of this project was to further the science of mussel propagation and culture and to increase the available resources to facilitate growout. During the project, we increased our lab capabilities and propagated 10 mussel species native to North Carolina. New host fish were determined for several of these species. Raceways for growout were established and evaluated at two state hatcheries, and we were able to culture 4 species to a size suitable for stocking. Additionally, progress was made in maintaining survival of some rare species which previously proved difficult to maintain in captivity. We worked to identify genetic markers, called microsatellites, in one species of mussel to facilitate tracking of propagated animals post-release</FONT><FONT face="Times New Roman"><FONT size=3>.</FONT></P></FONT>
G. Dennis PipkinJuly 2004 - June 2006
102
Complete
1
2006-37
89
  
1261082005Traffic & SafetyMiscellaneousDesigning an Efficient Nighttime Sign Inspection Procedure to Ensure Motorist Safety
<P><FONT face=Verdana size=2>During 2001-2002, the proposed research team conducted a research project for the NCDOT focusing on determining the optimum strategy for sign inspection and replacement under different conditions to respond to pending retroreflectivity requirements the FHWA will likely impose (9, 10). Toward the end of that project, a simulation tool to quantitatively evaluate the effectiveness of different sign inspection and replacement scenarios was developed. The simulation was designed for yellow and red engineer grade sign sheetings, and takes into account sign vandalism and knock-downs as well as normal sign aging. The simulation estimates the number of signs in place that would not meet the minimum retroreflectivity standard and the cost of the sign inspection and replacement program.<BR><BR></FONT><FONT face=Verdana size=2>The results from a number of trials of the simulation show that agencies that generally conform to the key assumptions made to build the simulation should consider replacing all signs every seven years, as that insures that no aged signs are in place at a relatively low cost. If total replacement is not possible, an inspection program using retroreflectometers every three years appears very competitive with a program using visual inspection of each sign each year. The retroreflectometers appear to allow fewer deficient signs, while the visual inspection program costs are lower. Visual inspections every two or three years allow relatively high numbers of deficient signs to remain on the roads.<BR><BR></FONT><FONT face=Verdana size=2>NCDOT may not feel comfortable using the simulation as it now exists due to one or more of the key assumptions that were made when building it. The purpose of this project is to remove those key assumptions and allow NCDOT to use the simulation with confidence. In particular, the model will incorporate the best possible sign deterioration functions available into the simulation, add the capability to analyze other types of signs besides yellow and red, and add data specific to the performance of NCDOT sign inspectors. With these additions, the simulation should be capable of saving the NCDOT hundreds of thousands of dollars per year in needless sign replacements, while insuring that motorists always see signs that meet minimum visibility standards.<BR><BR></FONT><FONT face=Verdana size=2>The major objective of the research is to revise and expand the simulation of the effectiveness of sign inspection programs so that NCDOT can optimize its program. The main revisions necessary to allow NCDOT to use the simulation are to:</FONT></P><br><UL><br><LI><FONT size=2><FONT face=Verdana>Model the performance of NCDOT sign inspectors,</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Expand the simulation to include other sign colors besides yellow and red, and</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Include the best sign deterioration functions.</FONT> </FONT></LI></UL><br><P><FONT face=Verdana size=2>The simulation model proposed herein utilizes various combinations of vandalism rates, deterioration rates, replacement cycles, and inspection methods to determine the costs of the sign management program and the number of signs that are not in compliance with retroreflectivity standards. Using this tool, the NCDOT can investigate various strategies to minimize cost, maximize the quality of signs on the road, meet the proposed new Federal retroreflectivity standard, and address liability concerns.<BR><BR></FONT><FONT face=Verdana size=2>Use of the simulation program by NCDOT may show that some changes are necessary in the current program to realize the cost savings, safety benefits, and other benefits described above. The NCDOT may need to hire more inspectors, train inspectors better, buy higher-quality signs, obtain retroreflectometers, improve inspector training, or make other changes. The outstanding feature of this research is that the NCDOT
Ron KingMustan KadibhaiJuly 2004 - June 2006
102
Complete
1
2006-08
90
  
1281102005Traffic & SafetyTraffic SafetyTraffic Control Design for Portable Concrete Barriers
<P><FONT size=2><FONT face=Verdana>The purpose of traffic barriers is to protect the traveling public as well as to provide a safe work zone for the construction crew on the side of the road. Design of the safe back distance has several implications. On the one hand, there is the issue of safety of the construction workers and the public. On the other hand, there is the issue of practicality and economic viability of highway construction projects. The North Carolina Department of Transportation (NCDOT) is currently in the process of developing its own traffic control design manual. The existing section on temporary traffic barriers requires calculating deflection of free standing barriers using an impact severity formula based on the Kinetic Energy principle. The design method, although approximate, is neither simple nor user friendly. Moreover, its applicability to the NCDOT and the Oregon Type F barriers, which the NCDOT plans to use, is very much questionable. <BR><BR>The objective of this research is to develop design aids, i.e., design charts and tables, for portable concrete barriers based on calibrated numerical analysis and rational design approach to be included in the new NCDOT traffic control design manual. Since both the NCDOT and the Oregon Type F barriers have been recently crash tested, only numerical analysis (and no crash test) is required for the design of both types of barriers. Once the physical impact problem is modeled and calibrated against the recent crash tests on both the NCDOT traffic barriers and the Oregon Type F traffic barriers, it can be used to determine the safe back distance as well as the length of need for free standing portable concrete barriers under different design conditions, including barrier type, design speed, vehicle mass, lane configuration, and roadway geometry, i.e., tangent or curved segments with different radii of curvature. The deliverable of the project is design aids for the NCDOT barriers and the Oregon Type F barriers for use in the NCDOT traffic control design manual. Benefits to the NCDOT may be realized as safety, cost-savings, and design efficiency on all roadway construction projects.</FONT><BR></FONT></P>
Joseph IshakMustan KadibhaiJuly 2004 - June 2005
102
Complete
1
2006-03
91
  
1282092005Pavement & MaintenanceVegetation Management and RoadsideHerbicide Options for Weed Management in the North Carolina Highway Wildflower Program
<P><FONT face=Verdana size=2>The wildflower species typically planted in the highly disturbed environment of a tilled bed are not very competitive with the aggressive weedy species that inhabit the state. Weeds are not only unsightly but they also compete with wildflowers for growth inputs and reduce wildflower stands, growth, and bloom production. Hence, control of weeds is a necessity in successful establishment and maintenance of wildflowers. The most widely used weed control treatment for establishing wildflower beds in North Carolina has been soil fumigation, typically with the highly effective fumigant methyl bromide. This procedure is very expensive, and it necessitates the use of unsightly plastic tarping. Moreover, production of methyl bromide, classed as an ozone depleter, will cease at the end of 2004. The loss of methyl bromide will create a serious void in the weed management program for wildflowers. Chemical weed control (herbicides) is the only feasible means of managing weeds in roadside wildflower plantings in the absence of fumigation. There are no biological controls for weeds in wildflowers, and other non-chemical methods are much too labor intensive and costly. </FONT></P><br><P><FONT size=2><FONT face=Verdana>The NCDOT is currently using a limited number of herbicides in wildflowers, but the herbicides used do not control many weed species encountered. There are likely other herbicides that could be used safely and effectively, as demonstrated by preliminary experiments currently underway by this proposal's author, but very little is known about the tolerance of wildflowers to most herbicides and the weed control possible. Research in this area is a critical need. Further, such research is needed to support registration of herbicides that have potential uses in wildflowers. Considering the multi-species plantings common along roadsides and the number of annual and perennial weeds encountered, it is quite likely that suitable herbicides cannot be found to handle every situation. Hence, research is also needed to investigate new fumigants, such as methyl iodide, as an alternative to methyl bromide. The proposed research will be designed to thoroughly investigate the use of herbicides and alternative fumigants in the establishment and maintenance of wildflowers. Results of the research will be used to develop weed management recommendations and educational programs for NCDOT personnel involved in wildflower management decisions.</FONT><BR></FONT></P>
David HarrisErnest MorrisonJuly 2004 - June 2007
101
In Progress
1
2006-60
92
  
1283112005PlanningTraffic Surveys, Modeling and ForecastingMulti-Year Travel Model Research
<P><FONT face=Verdana><FONT size=2>To simplify, streamline and standardize the travel demand modeling process we propose to develop guidelines for best practices for developing travel demand models and sub-models for trip generation, distribution, mode choice and assignment. In addition, we will develop recommendations for sources of relevant data, i.e., socioeconomic data, and we will undertake various kinds of validations of forecasts. These products and associated tools will help assure that NCDOT staff members efficiently use their time and resources to carry out their statewide transportation planning and modeling mission.<BR></FONT><BR></FONT><FONT face=Verdana size=2>The study will last three fiscal years will have two phases of approximately 1.5 years each. In Phase I, instead of using the same expensive transportation, air quality and impact and analysis approach for all communities, we propose developing appropriately scaled approaches that reduce time and cost, yet provide adequate estimates of traffic volumes and impacts resulting from new transportation projects. For example, conventional NCDOT trend line traffic forecasts are adequate for isolated highway projects in very small communities and rural areas. In towns with populations between 1,000 and 5,000, traffic forecasts and manual allocation methods are appropriate. As the size of the study area grows, quick response software is valuable. Our research will determine what thresholds might be appropriate for quick-response methods. Such software often uses national averages for travel demand model parameters and significant data collection savings accrue. The research team will adjust national averages to North Carolina values as necessary based on analysis of North Carolina travel data. We will focus on the quick response methodology used in TransCAD, as NCDOT is already heavily invested in TransCAD. Phase II will deal with guidelines and tools for larger areas. As the study area becomes larger including one or more MPO's or RPO's with multiple modes, TransCAD software will be the recommended tool following current NCDOT practice. However, we anticipate that efficiencies are possible through standardized GDSK sub-models and GIS displays.<BR><BR>We propose a flexible multi-phase, multi-year research program that captures the expertise of NCDOT, the TRM Service Bureau, and the two Universities. Besides producing specific guidelines for using alternate travel demand model approaches depending on community size and/or needs, we will identify and develop sub-models and tools for carrying out travel demand model analysis.</FONT></P>
Rhett FussellG. Dennis PipkinJuly 2004 - June 2007
101
In Progress
1
2006-58
93
  
1301122005PlanningPublic & Rural TransportationBenchmarking for North Carolina Public Transportation Systems
<P><FONT face=Verdana size=2>Benchmarking is a process to establish standards, targets and/or best practices in regard to performance measurement. Performance measures are of most use when they can be compared to something else. In benchmarking, comparisons are usually made with one or more of the following: 1) some kind of industry standards; 2) appropriate organizational goals or targets; 3) the performance of a peer group; or, 4) the "best practices" of other similar organizations.<BR><BR>This research study will provide three primary products:</FONT></P><br><OL><BR><br><LI><FONT size=2><FONT face=Verdana>A set of selected benchmarks for public transit systems, particularly efficiency and effectiveness benchmarks that are commonly used by other transit systems or benchmarks that specifically relate to important customer satisfaction factors identified as part of the study.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>A recommended benchmarking process that can be used by public transit systems in North Carolina to identify areas of low performance and then institute steps to improve it.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Implementation of an Internet listserv that will provide a communications method to share and disseminate information on, and questions about, benchmarking activities and best practices.</FONT> </FONT></LI></OL>
Miriam PerryMrinmay "Moy" BiswasJanuary 2005 - December 2005
102
Complete
1
2006-33
94
  
1321132005Pavement & MaintenanceAsphalt Mix DesignDevelopment of APA Design Criteria for Surface Mixtures
<P><FONT face=Verdana size=2>Several test methods are in practice to assess the rutting potential of a mixture. The commonly used procedures are Diametral tests, Uniaxial test, Triaxial tests, Shear tests, Empirical tests, and Simulative tests. Of all these test methods, simulative test methods are relatively easier to use and ready for immediate adoption. The APA test is the most widely used simulative test. It is imperative that the rut depth criteria for the APA test should be developed for its employment. In a recent study conducted at NCSU, it was concluded that the APA could clearly detect poorly performing mixtures. With the limited availability of data, a reasonable correlation was observed between the APA tests and Repeated Shear at Constant Height (RSCH) tests. In view of this, a comprehensive research study should be conducted on all the surface mixtures used in North Carolina to develop the rut depth criteria. The rut depths measured from the APA tests would be compared with the corresponding shear strains of the RSCH test. Statistical analysis would be performed on the test results as measured by the APA and the RSCH tests. In addition, the APA test would be fine-tuned by addressing many issues related to air voids, test temperatures, gradations and aggregate sources. The correlations estimated using the data obtained from the APA and Shear tests would be used to develop rut depth criteria for the APA test. The developed rut depth criteria for the APA test could be adopted for immediate use in practice.</FONT></P><BR><br><P><FONT face=Verdana size=2>The primary objectives of this research study will be to:</FONT></P><br><OL><br><LI><FONT size=2><FONT face=Verdana>Conduct APA and Shear tests on all the surface course mixtures used by the NCDOT.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Develop correlations of Shear tests and APA test data.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Fine-tune the APA test by considering different air voids, test temperatures and <BR>aggregate sources and quantify the effect of these variables on the predictability of the APA.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Develop and recommend the APA test criteria for evaluation of rutting potential of the mixtures.</FONT> </FONT></LI></OL><BR><br><P><FONT face=Verdana size=2>The proposed study will provide a simple and effective methodology and design criteria for using APA for Superpave surface mixtures. The rut depth criteria could be implemented for all the new surface mix designs and test contractor submitted specimens for compliance. The implementation would result in better overall pavement performance and possibly less rutting in HMA pavements in North Carolina.</FONT></P>
Todd WhittingtonMustan KadibhaiJuly 2004 - June 2006
102
Complete
1
2006-40
95
  
1322142005Pavement & MaintenancePavement PerformanceTensile Strength - A Design and Evaluation Tool for Superpave Mixtures
<P><FONT face=Verdana size=2>Evaluation of a mixture's moisture sensitivity is currently the final step in the Superpave volumetric mix design process. The presence of water (or moisture) often results in premature failure of asphalt pavements in the form of isolated distress caused by debonding of the asphalt film from the aggregate surface or early rutting/fatigue cracking due to reduced mix strength. The damage due to moisture is controlled by the specific limits of the tensile strength ratios (TSR) or the percent loss in tensile strength of the mix. Loss in the pavement strength due to moisture damage indicates that the individual tensile strength of the mixtures after conditioning will govern the rutting and fatigue life of the mixtures. A total dependency and reliance on the TSR values only may be misleading in many cases. There has been no concerted effort at national or state level towards establishing the quantitative causal effects of failing to meet the minimum prescribed value of TSR or loss in tensile strength. Tensile strength plays an important role in the performance of a mixture under fatigue, rutting and moisture susceptibility. A recent pilot research study conducted at NCSU has shown that there exists a relationship between the indirect tensile strength of a mixture and its estimated fatigue and rutting life. A minimum tensile strength value can be calculated at a given traffic level for fatigue life and an allowable rut depth for rutting and can be used as an additional criterion for evaluating the moisture susceptibility of a mix. Thus, the individual values of tensile strength of conditioned and unconditioned specimens along with TSR values should be employed in assessing the effect of water damage on the performance of pavements.</FONT></P><BR><br><P><FONT face=Verdana size=2>The primary objectives of this research study will be to:</FONT></P><BR><br><OL><BR><br><LI><FONT size=2><FONT face=Verdana>Evaluate the tensile strengths of conditioned and unconditioned specimens and their tensile strength ratios (TSRs) for mixtures with different aggregates and gradations.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Conduct a comparative study on the effects of hydrated lime and a liquid anti-stripping agent on tensile strength and TSR values of the mixtures.</FONT> </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Develop the relationship between the tensile strength for mixtures with different aggregates and gradations and their fatigue performance as estimated using the Frequency Sweep Test at Constant Height, Diametral Tensile Fatigue Test and Indirect Tensile Test.</FONT> </FONT><BR><br><LI><FONT face=Verdana size=2>Conduct a detailed study to investigate the rutting performance of mixtures with different aggregates and gradations using the Repeated Shear Test and Constant Height and develop its relationship with the tensile strengths of the mixtures. </FONT><BR><br><LI><FONT size=2><FONT face=Verdana>Develop a minimum tensile strength criterion along with TSRs for mixtures with different aggregates and gradations.</FONT> </FONT></LI></OL><BR><br><P><FONT face="Verdana, Arial, Helvetica, sans-serif" size=2><FONT face=Verdana size=2>The proposed study will provide a simple, reasonable and dependable method for mix design and performance evaluation of Superpave mixtures. The minimum tensile strength criteria developed from different correlations could be used along with the TSR values as a part of the Superpave mix design criteria.</FONT><BR></FONT><FONT face="Verdana, Arial, Helvetica, sans-serif"></FONT></P>
Jack CowsertMustan KadibhaiJuly 2004 - June 2006
102
Complete
1
2006-24
96
  
1341152005Pavement & MaintenancePavement PerformanceUse of Lime as Anti-strip Additive for Mitigating Moisture Susceptibility of Asphalt Mixes Containing Baghouse Fines
<P><FONT face=Verdana size=2>Presently, in North Carolina the bag-house materials used in hot-mix-asphalt (HMA) are purged intermittently into the AC mixtures rather than being stored in a silo and added to the mixture as mineral filler in a uniform, controlled manner. Previous studies have shown that the volumetric properties of asphalt mixtures are greatly influenced by the source and gradation of the baghouse fines. Due to this reason, several states require contractors to waste baghouse fines. However, there is some environmental concern in wasting the fines.</FONT></P><br><P><FONT face=Verdana size=2>Recent NCDOT research suggest that baghouse fines with gradation similar to the natural and manufactured fines passing #200 sieve, seems to have beneficial effect on stiffness and rutting characteristics of the asphalt mix. However, these studies conclude that mixes containing baghouse fines were highly moisture susceptible, and recommended that baghouse fines be metered into the mix to create a uniform percentage throughout the mix.</FONT></P><br><P><FONT face=Verdana size=2>This research proposes to conduct a laboratory study of moisture sensitivity of asphalt mixes containing controlled percentages of Boone and Enka baghouse fines in the amount of 0, and 4-percent. In this study, lime will be used as an anti-strip agent to determine its effectiveness in mitigating moisture damage. The results of this study will complete, and support the outcome of the previous NCDOT studies that investigated mitigation of moisture susceptibility of mixes containing baghouse fines with organic anti-strip additives. The recommendations based on results of this study should enable NCDOT to formulate specifications with regards to the use of baghouse fines in NCDOT mixes. Three possible outcomes that may be pursued are: 1) waste baghouse fines all together; 2) require use of baghouse fines in uniform controlled manner; 3) require use of lime as anti-strip additive in lieu of the use of organic anti-strip additives.</FONT></P><br><P><FONT face=Verdana size=2>The objective of this research will be to evaluate the use of lime as anti-strip additive for mitigating the moisture susceptibility of asphalt mixes containing baghouse fines. Two baghouse fines - Boone and Enka that has been used in prior NCDOT studies [2, 3] will be evaluated. This will allow direct comparison of the same mixes containing organic liquid anti-strip with those containing lime as anti-strip.</FONT></P><br><P><FONT face=Verdana size=2>The anticipated results of this research study will be a clear understanding of the significance of the use of baghouse fines in asphalt mixes used in the state of North Carolina, vis-à-vis comparison between mixes containing lime and organic anti-stripping agent.</FONT></P>
Judith Corley-LayMustan KadibhaiJuly 2004 - June 2005
102
Complete
1
2005-13
97
  
1342162005Structures & ConstructionMiscellaneousDevelopment of an Earth Pressure Model for Design of Retaining Structures in Piedmont Soils
<P><FONT face=Verdana size=2>The lateral earth pressure on retaining structures due to Piedmont residual soils is difficult to quantify by traditional methods and is often over predicted. Thus, large safety factors are used in retaining structure design that increase conservatism but not necessarily the engineer's confidence in the design. Much of this conservatism can be attributed to the divergence between the behavior of Piedmont residual soils and traditional cohesive and cohesionless soils. <BR><BR>The objective of this proposed project is to develop a simplified model for lateral earth pressure in Piedmont residual soil based on insitu soil tests. This model will be determined by measuring the lateral earth pressure behind sheet pile retaining walls in three of the geologic zones of North Carolina: the Carolina Slate Belt, the Charlotte Belt, and the Inner Piedmont.<BR><BR>A novel approach using instrumented sheet piles as "moment-cells" will be adapted from the analysis of piles under lateral loading. Sheets will be instrumented to measure bending moment and slope, and through differentiation, the shear stress in the wall due to earth pressure will be determined. To include the effect of joint orientation within the residual soils, an approach is proposed to bracket the two extreme conditions (joints dipping in and joints dipping out of the excavation) at each test wall site. <BR><BR>Based on the results of the research program, a simple lateral earth pressure model will be developed that will be a function of easily measured insitu soil properties and the joint fabric characteristics of the residuum.</FONT></P>
Scott HiddenErnest MorrisonJuly 2004 - June 2006
102
Complete
1
2006-51
98
  
1343172005Structures & ConstructionBridge DesignFuzzy Neural Network Models for Geotechnical Problems
<P><FONT face=Verdana size=2>The main objective of the proposed research is to: (i) develop a general framework and a computational toolbox for development of fuzzy neural network models to geotechnical problems, and (ii) to develop a fuzzy neural network model for the development of pile driving criteria related to hammer approval. <BR><BR>The following products are expected to result from the proposed study: (a) a general framework and a toolbox for development of fuzzy neural network model for a typical geotechnical problem, and (b) a trained model for the development of pile driving criteria. The model will be implemented in form of user friendly software with a convenient graphical user interface (GUI). A user friendly manual will also be developed. A brief training module will also be provided. <BR><BR>Once this study is completed other specific models can be easily developed for other specific problems. Since this new approach of modeling is based on observational data, and NCDOT has at its disposal good data bases for several problems, it is expected that this study will facilitate the development of specific models for several other problems of interest to NCDOT engineers. These models will be capable of incorporating the accumulated experience of NCDOT engineers. This will also lead to development of organized databases for several significant problems.</FONT></P>
Mohammed MullaErnest MorrisonJuly 2004 - June 2005
101
In Progress
1
2006-52
99
  
1361182005https://apps.ncdot.gov/Projects/Research/SearchResult.aspx?CID=84Bridge ConstructionFull Scale Testing of Overhang Falsework Hangers on NCDOT Modified Bulb Tee (MBT) Girders
<P><FONT face=Verdana size=2>To ensure the safety of the construction workers and personnel in bridge construction areas, the proper design and detailing of bridge overhang falsework is essential. In the design of the overhang falsework systems, a problem has been identified by NCDOT design engineers. The problem is in the determination of the ultimate strength and safe working load capacity of falsework hangers on modified bulb tee (MBT) prestressed concrete girders. The hanger manufactures require 5 inches of concrete to embed the hanger and develop the strength into the flange. The MBT girders have a top flange thickness of 3 ½ inches. This results in reduced safe working loads or the use of bearing plates to distribute the forces over a larger area of the flange. The analysis procedures used by the manufactures and NCDOT to predict the strength of the hangers on MBT girders are not consistent and may have resulted in conservative and more costly falsework designs. The focus of this proposed research is to determine the ultimate strength and safe working load capacity of falsework hangers on MBT girders through full scale testing. In addition, an analytical investigation will be performed to develop analysis and design guidelines and detailing recommendations. The results of this study can be directly integrated in the NCDOT design standards for use by contractors and in-house personnel. This will result in more cost-effective falsework system designs.</FONT></P>
Greg PerfettiMrinmay "Moy" BiswasJuly 2004 - June 2005
102
Complete
1
2006-12
100
  
1381192005Structures & ConstructionBridge DesignPile Bent Design Criteria
<P><FONT size=2><FONT face=Verdana>Pile foundations are normally used to support bridges and are subjected to axial and lateral forces produced by dead loads, winds, traffic, waves, and ship impacts. Support configuration takes the form of a pile bent where the support members extend from the superstructure continuously below grade. Support members such as this are often termed 'pile-columns.' Resistance, within each bent, arises from pile-soil-pile interaction, and pile cap carrying capacity components. For pile foundation design, the current practice of NCDOT is to specify a long enough length to provide a point of fixity (along the length of the pile) on the basis of 1 inch lateral deflection at the top of the pile bent. The pile bent is then analyzed using frame analyses to estimate bending moment and shear forces for structural design. An equivalent length K-factor of 2.1 is assumed in the longitudinal direction (assuming free head conditions) while a K-factor of 1.2 is used in the transverse direction (assuming translation with no rotation). The shear and moment computations using frame analyses do not consider the presence of the soil around the pile from the point of fixity to the ground surface. In addition, the one-iteration moment distribution analysis does not properly take into account the impact of pile cap rigidity on the distribution of the applied load to each pile within the bent. As has been recognized by NCDOT, such limitations are excessively conservative and lead to costly specifications. <BR><BR>The objective of this study is to develop improved analysis criteria for design of pile bents in a cost-effective manner while maintaining adequate safety margin. Specifically, the work will be focused on the following aspects: i) Evaluating the impact of the pile cap rigidity in the transverse direction, and superstructure rigidity in the longitudinal direction to loads transferred to each pile within the bent, ii) Specifying appropriate K-factors for pile analysis under varying boundary conditions appropriate to the problem geometry and boundary connection scenarios, iii) Proposing appropriate "point of fixity" taking into account the presence of the soil around the pile from the ground surface down to the point of fixity, and, iv) Proposing appropriate values for maximum lateral deflection and pile shear capacity for various structure types and soil properties in order to achieve 'uniform risk' designs. The proposed work will be accomplished through a combined structural and geotechnical effort as the scope is truly an issue of soil-structure interaction. The scope will also require both detailed finite element analysis, and simplified frame analysis, for assessment of design recommendations. The analysis model will be developed using the finite element analysis software, ANSYS, which will be utilized to build model for the pile bent with the surrounding soils. The use of other programs such as FL -Pier will be explored once their robustness is confirmed. The computer programs Response 2000 and ANDRIANNA will be utilized to model the structural cross-sections and provide details required for implementing a simplified 2D plane frame analysis for estimation of pile forces, moments, and lateral deformations, as well as for aiding in the estimation of pile member limit state. While these advanced computer programs are available in the market and will be utilized for analysis of the pile bent, columns and foundation in this proposed work, it is not the intent of this research to change the current practice tools of NCDOT, but rather to explain limitations and opportunities and recommend ways for using NCDOT tools more efficiently.</FONT><BR></FONT></P>
Greg PerfettiMrinmay "Moy" BiswasJuly 2004 - June 2005
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