~ 1951 Bridge over Cashie River needs to be replaced.
~ Existing bridge terminates at a busy Tee-intersection, which will necessitate a flared curved end of bridge or approach slab.
~ The proposed bridge will need to be wider to accommodate wide turns by tractor-trailers.
~ There is a pump house adjacent to the bridge on other side of the Tee-intersection. In addition there are two large utility lines supported on the bents on each side of the bridge.
~ Roadway will design the approaches so that the critical corners of the bridge are protected.
|2005||2005_Site13A||1||Bertie, ||Add-on Bertie county||East (Piedmont/Coastal)|
~ Location now has a high ADT count.
~ Sidewalks on both sides of the bridge
~ There were no deck drains to rapidly remove water from the roadway surface.
~ There was some spalling on the under side of bridge starting with slab units 3 through 5 and in some areas 7.
~ Based on the observations asphalt overlays on box beams and cored slabs on high ADT/ADTT and high salt application locations may not be the best product.
~ It was suggested that the Department consider overlay systems that will better protect the superstructure.
It was noted that quality control for producing cored slabs has improved, e.g. more cover for strands on the bottom is now required.
~ In addition, the Materials and Tests Unit has refined the asphalt super-pave mixes. Mixes are not as coarse and therefore not as permeable as some of the earlier mixes.
~ It was noted that the Department usually details 4" f through-the-rail drains, which are generally not very efficient for rapid drainage and generally and allow salt to permeate and accumulate in the asphalt.
~ FHWA suggested that the Structure Design Unit develop criteria for use of concrete overlays with consideration for location and traffic counts.
~ In addition, the Structure Design and Construction Units will use 8" wide x 4" tall drainage slots on a trial basis.
~ It was also suggested that the Materials and Test Unit take asphalt cores from a variety of cored slab bridge overlays and test for chloride content to severity of chloride ingress.
~ The Hydraulics Unit noted that there were lots of trees leaning in to the creek, and therefore A-frame bents would not be recommended due to potential for debris accumulation.
|2005||AtlanticAve_CrabtreeCreek||5||Wake, ||Bridge # 342 - Atlantic Ave. over Crabtree Creek|
Cored Slab built in 1972. ADT = 30,000
~ Concrete footings were unusually large - appeared to be overdesigned.
~ Sidewalk cover plates had large gaps - a tripping hazard.
~ A Veterans memorial park is to be created adjacent to bridge.
~ Electrical wiring not in conduit was detailed in the plans.
~~ There were concerns over the long-term implication of not placing wiring in conduit.
|2005||B-2548F||1||Washington, ||Bridge on US 64 over the Scuppernong River|
Pedestrian crossing was recently completed at this site. Many other unique items on this structure, which include concrete flowable fill, metallized pipe piles, and wick drains.
~ Bridge appears to have deteriorated over the past three years.
~ The fall protection on the fishing walk was in need of repairs.
~~ Raised questions regarding who maintains the fishing walks.
~ A-jacks did not appear as large as expected, but delivery matched plans.
Repair was an emergency and this size was specified because they were in stock and could be delivered more rapidly.
|2005||B-2500||1||Dare, ||Bridge #11, Bonner Bridge, NC 12 over the Oregon Inlet||East (Piedmont/Coastal)|
Stainless steel appeared to have weathered slightly.
|2005||WrightBrosMemorial||1||Dare, ||Wright Brothers National Memorial, Kill Devil Hills|
Sculpture was commissioned for the 2003 centennial celebration of the Wright Brothers flight. DOT Structure Design personnel performed the structural design of the full-scale airplane sculpture.
~ To correct large joint opening, the contractor removed initial 1½" layer of asphalt base, installed ¼" think metal plate to bridge the joint, and applied the polymeric material up to the thickness of the asphalt base. Entire joint was then paved over with the final asphalt layer as usual.
~ The asphalt over several of the joints appeared to have cracked less than is typically seen on an asphalt overlaid cored slab bridge.
~ The joint with the polymeric material appeared to be developing cracks on either side of the embedded plate over the joint.
~~Concerns were raised over the asphalt over the metal plate will spall out if the dual cracks continue to develop.
~ In an attempt to alleviate the cracking observed in the asphalt overlay, on a trial basis the Construction Unit will fix both ends of each span on short cored slab bridges prior to placing the asphalt overlay
|2005||B-3435||1||Chowan, ||SR1207 over the Rockyhock River|
Cored slab bridge with asphalt overlay. Several joints were over 3" wide and could not be paved across. Fabric was installed and Applied Polymeric Joint (a proprietary product similar to elastomeric concrete) was used. The joints have been in place for 6 months to a year. Foam fill, which was used in the embankments, was damaged during a hurricane tidal surge and required repair.
~ Existing 50 foot, 3-span timber girder bridge over the Great Swamp needs to be replaced.
~ The current structure recommendation shows a 3-span 90 foot cored Slab Bridge.
~~ The Hydraulics Unit noted that the shallow low flow conditions as well as lack of trees leaning into the flow channel made the site suitable for A-frame bents.
~ The possibility of spanning the swamp with a 70' box beam structure was discussed.
~ This option would require raising the grade by approximately 6".
~ In general it was agreed that the Department should consider alternate designs to eliminate piers.
~ The FHWA noted that there are many instances where load postings are on bridge, and therefore any vehicle that may exceed the posted load would have no advance notice of the maximum load allowed on the posted bridge.
|2005||B-4319||4||Wilson, ||Bridge #21, on NC 222 over the Great Swamp|
Proposed 3-span, 90-foot long bridge with a 90° skew. The 3-span bridge shall be a top-down construction with an offsite detour. The subsurface consists of high blow count sand. There is an in-water moratorium until June 15th. A single span bridge would be preferred.
~ Concrete Girder Bridge on Faison Road
~ 2-span continuous modified bulb-tee girder bridge, with each span 140+ feet long.
~ The deck had been poured except for over the bent, where it had been formed up for the continuous for live load diaphragm and slab.
~ During the main deck pour the long girders deflected more than anticipated.
~ In the area over the bent, the reinforcing steel appeared to have more than the standard 2½" of concrete cover.
~ The deck slab was had a few visible cracks near the end bent.
~ It appeared that the structure will carry a future sidewalk, so there were no dowels cast into the deck slab.
~ Each span had a single line of steel diaphragms.
~ There were questions on the appropriate amount of tension applied to the diaphragm bolts?
~ Steel bridge over US 64
~ Noted various configurations for tall MSE walls:
~~ Wall with reversed wing walls and a single row of piles (on Knightdale Bypass project by Design-Build team).
~~ Wall with turn back, skewed wing walls and battered piles (on Wake Forest Bypass by in-house staff).
~~ Wall that follows the end bent envelope and the cap is supported on a double row of vertical piles.
~ Potential for settlement of embankment should be examined during design of MSE wall.
~ MSE walls with reversed wing walls raises some drainage issues, and
~ Consideration of ease of future inspection.
|2005||KinghtdaleBypass||5||Wake, ||New section of US 64 just east of Raleigh|
Project with numerous structures that include many items of interest such as very tall MSE walls, work bridges, long span (140'+) bulb-tee girders, and steel intermediate diaphragms on prestressed girder structures.
~ New procedure has been developed to ensure the required roadway requirements are met.
~ The contractor expressed numerous girder layout and constructibility issues.
~ It was suggested that where possible the Department utilize rectangular bridges in lieu of SPUIs.
~ Noted MSE wall geometry, where the end bent cap is offset from wall versus the cap "sitting" on the wall.
|2005||R-2809B||5||Wake, ||Wake Forest bypass over US 1 (Capitol Blvd.)|
This project has a Single Point Urban Interchange (SPUI) bridge, giving the bridge deck an hourglass shape. The project had several construction and geometric problems resulting in reduced roadway clearances.
~ This Project was initially scoped as a culvert.
~ Steep end slopes with rock embankment (class 7 rip-rap),
~ The alternative was to install fabric wall slope stabilization
~ Bent in stream required permit modification to divert stream channel.
~ It was noted that during your tour of this site the metal SIP forms were being placed before cast-in-place concrete diaphragms.
|2005||2005_Site16A||5||Wake, ||Add-on Wake Forest bypass over US 1 (Capitol Blvd.)|
This project has a Single Point Urban Interchange (SPUI) bridge, giving the bridge deck an hourglass shape. The project had several construction and geometric problems resulting in reduced roadway clearances.
~ There were several bolts missing from angles that secure the noisewall panels in place
~ Cracking observed on the barrier rail.
~~ Some to this cracking is normal, and in this case the cracks happen to coincide with the embedded noisewall assembly pockets. Some pockets may have to be repaired.
~ The Bridge Maintenance Unit expressed concerns over the number of available panel suppliers and proprietary product issues.
~~These concerns may lead to the possibility of having to stockpile spare panels for possible future repairs to the noise wall.
|2005||I-306C||5||Durham, ||I-85 over Club Boulevard|
The bridge over Club Boulevard includes a noisewall attached to the back of the barrier rail. Other municipalities are looking into doing something similar at other sites.
~ Cored slab units did not appear to have significant damage from below.
~ The bridge had an asphalt overlay with evidence of repairs over the joints
~ There was evidence of some leaking over the joints
~ The substructure appeared to be deficient.
~ Sheet flow of drainage over the side of cored slab units did not appear to affect the exterior faces of the cored slab units.
~ The Structure Design will develop policy on when a concrete overlay should be considered.
~ In addition, the department will conduct further investigations of cored slab bridges in service
~ The Bridge Maintenance Unit will assemble a list of cored slab bridges.
|2005||Bridge#36||5||Durham, ||SR 1671 (Camden Ave.) over a creek|
Cored slab structure built by the Bridge Maintenance Unit in 1967. Current ADT is 1700 vehicles.
~ Use of very tall galvanized pipe piles, which had lots of visible repairs to the galvanizing.
~ FHWA inquired if NCDOT ever fills tall pipe piles with reinforced concrete. The Department does not fill pipe piles with concrete.
~ In response to a question about the economy of pipe piles, the Geotechincal Unit stated that they would recommend their use in more locations if the Department had standard drawings for 18", 24", and 30" diameter galvanized or metallized pipe piles.
~ It was suggested that the Structure Design Unit develop a standard drawing for 12" pipe piles to replace 12" "H" piles because the pipe piles will allow for using shorter piles since close ended pipe piles can develop significant end bearing in addition to skin friction.
~ For the drilled piers on this site, polymer slurry was used to stabilize the excavation.
~ Steel girder flange splices had as many rows of bolts as the web.
~ It appeared that the girder span lengths could have been longer.
~ The Construction Unit noted the need to detail a for short "knee" wall on decorative rails to allow contractor to level up forms and make adjustments for variations in elevations in the deck so that the top of the rail will be at a constant elevation. It was also noted that decorative rails add time to contract period.
~ This site had several utilities adjacent to the bridge. It was noted that in most cases it is better to relocate utilities that are impede construction activities. However, it was recognized that the owners often don't have sufficient funds for relocation, but in general the utility owners would permit relocations if the Department will pay for them.
~ A permit modification was required for barge landing because it was omitted in the original permit
|2005||B-3442_B-3443||6||Cumberland, ||SR 1006 over the Cape Fear River|
5-span steel structure with classic rail
~ The majority of the end bent slope very damp due to subsurface water.
~ End slope sloughing off mostly on one side of the end bent.
~ Repairs performed to date have been ineffective.
~ It appears that the class of rip-rap slope protection was too small or not the appropriate size.
~ For some sites, such as this one, provisions for ground water drainage may be necessary.
|2005||R-2562AA||6||Cumberland, ||Bridge #21 on NC87 South of I-95|
Existing structure has been open to traffic for several years. The bridge is exhibiting severe slope failure under the end bents and the pile foundation is exposed. The slope failure occurred after the project was accepted. Slope failure appears to be a result of high ground water.
~ 2-span (25' - 50') cored slab bridge with precast NJ shape barrier rail with cast in place barrier rail transition, and a 6% superelevation.
~ The bridge is in a location with a low sag vertical curve with potential for overtopping.
~ Minimal approach roadway work was appropriate for the scope of the project
~ Demonstrated a reasonable balance between bridge length and maintaining the grade.
~ Demonstrated that approaches do not need to be widened for bridge with large shoulders.
~ Bridge is a good example of a situation where a single span box-beam superstructure would have been appropriate.
~ The new process document will include details on how the Structure Design Unit will interact with Hydraulics in order to eliminate undesirable span arrangements.
~ Develop guidelines to determine situations where widening roadway approaches is appropriate,
~ Roadway Design and Structure Design Units should not design bridges for more than 2 lanes if the approach roadway is only two lanes,
~ In some situations allow shorter approach slabs in lieu of the current 25'-0". A suggestion is to base the approach slab length on the design ADT.
|2005||B-3167||3||Duplin, ||SR-1723 over Cabin Creek|
Bridge Maintenance Unit Purchase Order Contract (POC) job. Contrast this project with normal TIP jobs, particularly how the Bridge Maintenance Unit handles roadway approach work on bridge replacements.
~ The existing bridge is relatively short with a causeway over the surrounding wetlands.
~There were questions regarding the length of the replacement bridge, foundation types and size, and the span arrangements.
~ The site geometry especially at the bridge landing, where there is a roadway intersection and some businesses, presented a significant challenge in providing sufficient under-clearance for the navigable waterway.
~~ Deeper girders would have required raising the grade, but it would have been difficult to tie back in to the approaches.
~~ Predicted scour resulted in waterline footings on piles.
~~ Relatively shallow layer of hard material resulted in A-frame interior bents
~~ There were several other concerns that were raised, but each discipline had cogent reasons for the resulting layout and design of the structure.
~ It was suggested that use of FB-Pier on projects with numerous challenges, such as this one, might allow the Department to design interior bents that are a lot less imposing.
~ Therefore on long coastal projects with waterline footings and lateral stability concerns the Department should consider alternate analysis approaches.
~ There were still questions as to who throws the flag for alternative analyses.
~ The group was in agreement that project schedules should not drive engineering decisions / designs.
~ FHWA inquired if this was a suitable location for jetting piles.
~~ It was noted that jetting is most suitable for Divisions 1 & 2 (coastal counties).
~~ Problems encountered when jetting for the Virginia Dare Bridge (Manteo) have been unduly generalized for all sites.
~~ However, the Department is still pursuing jetting. A Special Provision, which specifies limits on containment for the contractor, is currently being developed. This will provide a starting point.
~~ The Department has proposed to perform jetting demonstrations/tests, which will be the basis for new jetting models for the certain/various soil types.
~~ Regulatory Agencies don't qualify zones in which jetting is not acceptable. In general they view jetting favorably, but they want to know how jetting will be implemented.
~~ FHWA recommends making jetting a priority.
|2005||B-2938||2||Carteret, ||Bridge #49 - SR1101 over the White Oak River|
A 2300-foot long Type II and Type IV prestressed concrete girder bridge. Several unique elements including 24" composite piles, 24" Dia. metallized pipe piles, closed drainage system, unarmored evazote joints with elastomeric headers.
~ 2-span cored slab bridge with a two bar metal rail.
~ The bridge had and "A"-frame bent which increases the potential for debris collection
~ This is a good example of a project where the Department did not excessively widen the bridge.
~ Tangent alignment and grade made this site suitable for limited work on approach roadway.
~ The Bridge Maintenance Unit suggested eliminating restrainer blocks on cored slab bridges that are detailed with dowels
|2005||B-3483||2||Jones, ||BRIDGE #19 -- SR 1004 over Mill Creek|
A small bridge replacement recently completed. This bridge is a good example of a project where the Department did not excessively widen the bridge compared to the bridge approaches.
~ Deck had a lot of surface type crazing cracks.
~ Over the bents, the deck was saw cut and silicone filled.
~ Lack of tooled contraction joints on 2BMR parapet had resulted in cracks in the parapet.
~ The bridge skew was set with flood flow direction not the normal flow direction.
~ The bridge was re-scoped and lengthened to bridge the surrounding wetlands. The skew could have been eliminated for the longer bridge.
~ This project demonstrated that in some situations the link slab is a viable alternative to a continuous for live load diaphragm.
|2005||R-2539B||2||Craven, Pamlico, ||Bridge on NC 55 over Upper Broad Creek|
A 12-span link-slab bridge, in which slabs were made continuous of the bents by debonding the slab at joint locations.
~ 1955 Swing span bridge.
~ Latest bridge replacement proposal is double leaf bascule bridge.
~ Questions raised included:
~~ What happens to the swing span island if the bridge is replaced with a double leaf bascule?
~~ Will a fender system be necessary for a single leaf or double leaf bascule?
~~ The Bridge Maintenance Unit would prefer to maintain single mechanism.
|2005||B-2532||2||Craven, ||Bridge #60, US 70 Bus. Over Trent River|
Trent River swing-span bridge built in 1955 is to be replaces with a new moveable structure by 2010. The current replacement scheme is considering a double-leaf bascule (drawbridge) to span the ~200' river channel. The new bridge substructure will be designed for vessel impact. The Town of New Bern would like the structure pained "Essex Green."
~ Asphalt cracking over the joints
~ Some of the prestressed piles had poor finish.
~ Cracking on acute corners of cored slabs on a skew.
~ Repairs performed with appropriate product from approved list (epoxy motar)
~ Bridge had horizontal drains through the rail at the ends of the bridge over the buffer zones.
~ For such a long structure, drainage could have been more efficient with a closed drainage system.
|2005||R-2548A||1||Tyrrell, Washington, ||Bridge on US 64 between SR 1119 and SR 1125|
Curved alignment on a widened cored slab structure with an asphalt overlay.
~ Had continuous for live load deck with little cracking
~ Joints (armor angles with elastomeric concrete headers) looked good, except on one end where there was some grinding that was required
~ Double row of closely spaced vertical prestressed piles
~~ Raised questions on the zone of influence / interaction of the closely spaced piles.
|2005||2005_Site9A||1||Tyrrell, Washington, ||Add-on Bear Bridge||East (Piedmont/Coastal)|
~ Contractor survey error resulted in low bent.
~ Up to 4" of lightweight concrete overlay were used to build up to required grade.
|2005||2005_Site9B||1||Tyrrell, Washington, ||Add-on Long Cored Slab Bridge with Low Bent||East (Piedmont/Coastal)|
~ Underside of cored slab units were in excellent condition, however there was some noticeable leakage between units.
~ Bridge roadway surface had excellent drainage via through-the-rail openings.
~ Bent caps were heavily stained due to leakage through large open cracks in the asphalt overlay over the bents.
~ Vegetation was growing along the gutter lines and in openings over the bents.
~ It was noted that this bridge was in an area where salt is seldom applied to the roads and bridges.
~ Bridges in areas where salt is applied more frequently do sustain damage from the salt, which eventually requires repairs.
|2006||Bridge#395||8||Chatham||SR1101 over Brush Creek|
Cored Slab built in 1970. Has an asphalt overlay. The 11 Cored slab units are 2’-9" x 1’-5". At 35 years old, this is one of the oldest cored slab structures in the state. Due to the relatively short time these types of bridges have been in service, their long-term performance and durability is a matter of concern.
~ 96" corrugated metal pipe culvert used under roadway.
~ Roadway shoulder width did not appear to be adequate.
~ Modular block headwalls were used to artificially shorten the length of the pipe culvert to avoid the need for a wetland's permit.
~ Some of the regulatory agencies are recommending this type of setup.
~ Many structures built by private developers, such as the culvert at this site, are installed without Department inspection oversight.
~ Most culvert inverts should be buried at least a foot. In this case invert should be buried two feet for scour reasons.
~ Several group members raised questions on the hydraulic efficiency of the pipe culvert installed at this site.
~ Is this type of wall suitable for any encroachment?
~ The Geotechnical Engineering Unit generally has no problems with the modular wall concept. However developers need to utilize approved systems, which are built according to Department policy and specifications. The Geotechnical Unit is developing a policy and specifications.
~ The Project Service Unit will be coordinating the policy on use of and approval of these types of wall systems.
~ Bridge Maintenance is not in favor of using modular walls as headwalls for culverts.
~ The Department's Subdivision Roads Manual needs to be updated.
|2006||SR1698||12||Lincoln||Near NC16. Residential (Webbs chapel Cove) street (SR1698) over a creek where segmental block walls were used as headwalls|
Contractors and Developers especially have shown a lot of interest in these types of proprietary, low-cost walls. Though these type of walls certainly have their place, there is some concern over their long-term durability in some applications.
~ One of the bents was designed for a post-tensioned integral bent cap. The design required 4 ksi. concrete strength prior to tensioning and 5 ksi. for the final strength. At 21 days the strength was 3.96 ksi. The contractor was waiting to see if 4 ksi would be achieved.
~ If design strength is not achieved, additional measures could include:
~~ Hiring a consultant to perform a cap rating for standard vehicles and super loads. This would be very helpful to the Bridge Maintenance Unit.
~~ Utilizing a lightweight concrete deck.
~ The Department should avoid utilizing post-tensioned integral bents, unless absolutely necessary. When necessary, ensure the following:
~~ Adherence to all restrictions before the allowing their use.
~~ Better consultant coordination during the design phase.
~~ The girders control the design and not the bent cap.
~ Hammerhead bents on the same project did not look uniform, due to designs by different consultants.
~~ Several planned large loop projects planned for the future will raise similar issues.
~~ Need more uniformity -- ensure better consultant coordination during the design phase.
~ The Construction Unit gave a detailed explanation of the complexities of screeding operations for the following conditions:
~~ Heavy skews.
~~ Transitioning superelevation on the bridge.
~~ Two bridges merging into one bridge.
~ The Roadway Unit stated that they try to avoid the conditions stated above whenever possible. However, it is not always possible, especially on big urban interchanges.
|2006||R-2248BC_R-2248D||10||Mecklenburg||Bridges over Long Creek and several grade separations at interchange.|
Span arrangement and bridge skew issues. Also, constructability issues with the deck and shoulder superelevations as designed.
~ Very good fit-up of the culvert sections.
~ Joints appeared to be watertight.
|2006||2006_Site11A||10||Cabarrus||Pedestrian Culvert - Town of Huntersville|
Three sided pedestrian culvert on footings
~ Very successful project that is suitable for fast-track construction. Saved over three months of construction time and could have saved more time.
~ Observed transverse cracks in the flange portion of the deck-girders. The cracks were located over a distance of 12-15 ft. from each end bent. The cracks have not propagated into the web. They appeared to be full-depth cracks due to observed moisture leakage on the underside:
~~ The Bridge Maintenance Unit inspectors will map cracks for monitoring purposes.
~~ Structure Design will request researchers to investigate the effects of negative moment at the integral end bents.
~ Since the deck is an integral part of the girder, care should be exercised on any future deck repairs.
|2006||B-3700||10||Stanly||Bridge #187 on SR 1214 over Long Creek, near Albermarle.|
This was partially funded as an IBRC project (Innovative Bridge Research project) in 2005. The single span 115 ft. structure was a fast track construction project, in which the superstructure consisted of 5 decked girders with embedded longitudinal angles in the deck/top flange. The girders were standard AASHTO Type III -- 45" prestressed girders, with an integral 6'-6" wide, 9" thick top flange that formed the bridge deck.
~ Site was very congested with utilities, drainage structures, the existing bridge, and the replacement bridge.
~ Hilfiker fabric wall utilized to shore approaches on the new bridge.
~ The fabric wall looked good with straight and fairly plumb walls with very little bulging.
~ The project will also include a 12 ft. soil nail wall in a cut section.
~ A value engineering proposal (VEP) to install a modular block wall with anchored temporary shoring has been submitted.
~ Anticipated traffic backups, which did not materialize, resulted in the contractor changing the traffic control plans to limit the time with a 2-lane pattern.
~ Due to the site congestion, 3-D CADD modeling would have been very useful for identifying conflicts.
|2006||B-3457||9||Davidson||I-85 Bus. Over SR1242.|
Staged construction of a bridge where fabric walls were used to build and shore the approaches. The site also required sheet pile shoring and a culvert extension.
~ Single span bridge at a site with unusual situation due to neighborhood involvement.E10- Rockline 10-15 ft. below the roadway.
~ Original design included 9 ft. tall piles supporting the end bent cap.
~ Roadway approach fill has been in place for several months.
~ Division requested an alternate design. Auger cast piles were considered.
~ The Department does not have much experience with them, and hence there was too much risk associated with their use at this site.
~ The revised design includes 8ft of reinforced select material supporting the end bent on a spread footing.
~ The Geotechnical Engineering Unit (GEU) will monitor any vibration and movement in the end bent for about a year.
~ Stress gauges buried in the embankment will record data at each stage of construction. GEU anticipates stresses will dissipate over time.
~ Vibration from grading operation may be comparable to pile driving.
~ Monitoring ground stresses and movement in the embankment will assist the Department in determining if the embankment on future projects could be built once. Currently, embankments are built up and the soil is allowed to consolidate during the waiting period. Then a portion of the embankment is excavated for construction of the end bent and placement of the reinforced approach fill.
~ Noise walls on bridge will be included at this site.
~ Silt fences failed near roadway.
~Would a 3-sided culvert on footings be a good option at this site?
~ Lighting in culvert would be a maintenance concern, and also possible graffiti problems.
~ Buried structures, especially prefabricated structures, have no well established method for rating.
|2006||U-2524AA/AB||7||Guilford||Greensboro Outer Loop - Kings Mill Road overpass|
This overpass is located near a subdivision. The Division Office is concerned about driving piles adjacent to the nearby slab-on-grade houses. Evaluated a variety of foundation types for the end bents to avoid the potential liability of vibration-induced damage. The site has a high rock line, and therefore auger cast piles were initially considered, but were considered too expensive. Next auger/driven piles (where the piles would be driven after auguring a short distance), but it was deemed still too risky.
Noisewall on bridge.
~ Repairs almost complete and the bridge is scheduled to re-open to traffic the day of the visit (5/9/06)
~ Barrier rails closed expansion joint over bent when bent rotated.
~~ Proposed to cut barrier rail to reopen expansion joint and alleviate further cracking. Lessons learned:
~~~ Good use of micro piles.
~~~ Good inter-Unit coordination.
~~~ Time to let could have been improved â€“ permit issues, rework contract.
~~~ Emergency permitting, contracting. First contract placed liability on contractor.
~ Revised contract reduced the scope of work and included more shared risk.
~~~ Respond quickly when we declare emergency.
~~~ Develop criteria for emergency permit, which may include:
~~~ How critical is this bridge?
~~~ Economic damage to area?
~~~ Emergency access risk?
~~~ Develop procedures for emergency bidding
|2006||Bridge#91||9||Forsyth, ||Over the Yadkin River|
Bridge foundation currently consists of spread footings in the water. Heavy current at this locale -- highest flood reading was 98,000 CFS. Bridge subjected to severe scour that caused the foundation to partially sink and rotate. Bridge is currently closed and a major scour retrofit and rehabilitation is underway. Retrofit utilizes micropiles as part of the foundation retrofit (bents 1-3). Eight 7 5/8" Micropiles per footing were installed, pile caps will be poured over them. Bent will not be re-rotated. Probably will rehab bridge rail and joint at rotated bent. During retrofit procedure, inspectors were monitoring rotation of pier with tiltmeters (inclinometers) and crack monitors. Access utilized about 2000 tons of rip-rap for the causeway. Wright Archer working with contractor to leave in cofferdam/sheet piles and will use rip rap from causeway for scour counter measures. Bent 5 was on rock and Bent 4 was on half rock/half weathered rock, so retrofit for these piers was unnecessary.