| | | | derivations AH. A complimentary term used in conjunction with the term "back" to label station equations. The ahead station signifies the station forward on the chain: -L- Sta 11+23.34 BK = -LREV- Sta 25+62.31 AH. |
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| | | Functional classification of roadway that is between an Interstate highway and Local collector. 
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| | | | Intersection where all proposed grades tie or projected to a common elevation. Conversely: grade separations (bridges) are required when the intersection is not at grade. |
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| | | | The average daily traffic on a roadway. Most Designers will label the current year ADT and the forecasted design year (usually 20 years from the construction year) ADT on a set of Roadway plans. ADT's is also one of the major criteria used used by Roadway Designers in the determining the dimensions and function of proposed roadways: relative formula [ADT = DHV/D]. |
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| | | derivations"BK." A complimentary term used in conjunction with the term ahead" to label station equations. The back station signifies the stations behind the equality on a chain: -L- Sta 11+23.34 BK = -LREV- Sta 25+62.31 AH. |
| | | Pavement Layer between the surface course or intermediate course layer and the subgrade (fine grade and compacted soil). Common base course: SP B25.0B and ABC.
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| | | synonym: girder. Steel or concrete superstructure members placed length wise along a bridge. Generally located between the bridge concrete slab and bent cap. Span types: Prestressed Cored Slab, Prestressed Girder, Prestressed MBT, Prestressed Box Beam, I-Beam, and Plate Girder.
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| | | Angle measurement used to label direction for horizontal alignments. Format: {North or South} {Angle in Degrees° Minutes' Seconds" from Respective N or S Axis}{East or West}; examples:
N 58° 36' 55.4" E  S 45° 22' 38.7" W 
For English projects, the accuracy of bearings is to the tenth of a second; N 11° 22' 33.4" E. For Metric projects, it is to the hundredth of a second; N 11° 22' 33.44' E.
Due North  is N 0° E or W;
Due South  is S 0° E or W;
Due East  is N or S 90° E;
Due West  is N or S 90° W. |
| | | type: interior and end bents. Bridge substructure composed of bent caps, columns, piles, and footings
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| | | synonym: structure. A structure 20 ft or more constructed to span over roadways, other bridges (flyovers), streams, wetlands, railroads, or any condition which requires a grade separation.. Other types: Cored slab: Cored slab bridges are noted because the bridge slab spans are cored or hollowed out.
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| | | synonym: intermediate course. Pavement Layer between the surface course layer and the base course layer.
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| | | ƒ3- synonym: flat back curves. The arrangement of two curves with a short tangent deflecting in the same direction. During night time driving or limited sight distance conditions, drivers normally do not expect successive turns in the same direction.Use of compound curves or a spiral transition is recommended in place of broken back curves.
Reference
ƒ3 - AASHTO "Green Book", 2004. |
| | | ƒ10 - Excavation volumes that are not backfilled with an earthwork material. This includes the excavation required for cut sections as well as for pavement thickness, shoulder thickness, etc.
Reference
ƒ10 - Geopak On-line Manual |
| | | ƒ9- The central angle subtended by 100 ft of arc. In railroad design, D is defined to be the central angle subtended by 100 ft of chord.
Reference
ƒ9- Surveying Principles and Applications, 3rd Edition.
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| | | ƒ1- geopak superelevation shape to which its starting grade point elevations dependends solely on the proposed profile. Also see independent shape, geopak shape, offset, and tie.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995. |
| | | ƒ1 - acronymn DDE 1. The classification of earthwork excavation amount used to grade to the proposed ditch grade line. DDE is a contigency item in the earthwork balance sheet.
ƒ7 - 2. [Excavation] to the line, grades, typical sections, and details [of drainage ditches] shown on the plans or established.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995.
ƒ7 - Standards Specifications for Roads and Structures, 2002. |
| | | ƒ1 - The process used to compute the amount of earth material (mainly soil) needed to completed the grading of roadway project. Project earthwork can be classified as either waste or borrow.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995. |
| | | ƒ1 - 1. The process used to dig up earth material (mainly soil) when the proposed roadbed is below existing natural ground. 2. The process used to grade a proposed ditch below existing natural ground. Also see Common Excavation, Subgrade Excavation, Subsoil Excavation, and Drainage Ditch Excavation.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995. |
| | | complex shape element placed in the shape file or model use for superelevation layout on proposed cross section templates. Both the horizontal (baseline) and vertical (profile) parameters are equally as important and necessary to create a shape for cutting cross sections or processing NCWedge runs. If the Designer needs run a preliminary superelevation layout without the creation of a proposed grade ready, then a real profile name with pseudo stations and elevations can be created to meet the requirements of the essence of a true geopak shape. See example COGO input of pseudo inputs.
Also see dependent shape, independent shape, MRG, offset, PGL, PGL chain, shape maker, and tie. |
| | | ƒ1- The effective point on a cross sections and typical sections where the profile grade is applied.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995. |
| | | crossing of two or more horizontal alignments separated vertically by control points relative to the vertical clearance height, plus the height of the bridge girder and bridge concrete slab (superstructure depth). Grade separations apply to roadway crossings as well as railroad crossing of roadway. Also see control point, substructure, superstructure, and vertical clearance. |
| | | ƒ2- the treatment and design of shoulder sections normally based on pavement design depth of greater than 10 inches.
Also see trench shoulder section.
Reference
ƒ2- The Roadway Design Manual. |
| | | geopak superelevation shape to which its starting grade point elevations is independent of the proposed profile. Independent shapes rely on the elevations of dependent shapes to extract elevation datum. Turning lanes are the appropriate applications for independant shapes. Also see dependent shape, geopak shape, offset, and tie. |
| | | ƒ1 - 1. The maximum allowable grade difference between the grade point (or center line) and the outside edge of travelway (EOT), used in the minimum length of runoff computation.
ƒ3 - 2. The maximum acceptable difference between the longitudinal grades of the axis of rotation and the edge of pavement. See ASSHTO 2004, pg. 177 for the minimum length of runoff formula using the MRG.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995.
ƒ3 - AASHTO "Green Book", 2004.
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| | | ƒ1- 1. The effective width for a divided facility on a cross sections and typical sections between the edge of travel (EOT).
ƒ3 - 2. The portion of a divided highway separating the traveled way for traffic in opposing directions.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995.
ƒ3 - AASHTO "Green Book", 2004. |
| | | ƒ1- 1. A roadway cut section with an applied special ditch grade.
2. A previously defined roadway fill section whereas the side slope has been extended at the same slope with an applied special ditch grade resulting in as a cut section.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995.
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| | | ƒ2- slope or crown section 1. A typical section whereas the grade point pavement slope begins at the centerline.
ƒ1 - 2. On a few divided facilities, whereas a PGL chain is used and/or having variable median widths, the grade point may sometimes be located in the center of roadway on each side of the median.
Reference
ƒ1 - The author, Oak Thammavong, worked in NCDOT Roadway Design since 1995.
ƒ2- The Roadway Design Manual. |
| | | ƒ9 - A transition curve of constantly changing radius placed between a high-speed tangent and a central curve; it permits a gradual speed adjustments.
ƒ8 - Typically, a minimum of 200' of spiral is required on interstate design.
Also see CS, run off, run out, SC, and superelevation.
Reference
ƒ8 - NCDOT Roadway Design Project Engineers.
ƒ9 - Surveying Principles and Applications, 3rd Edition. |
| | | ƒ10 - Excavation volumes that are backfilled with an earthwork material.
Reference
ƒ10 - Geopak On-line Manual. |
| | | ƒ10 - Excavation required to remove unsuitable material either 1. down to the bottom of the proposed template or 2. down to the bottom of the unsuitable material layer in cases where excavation limits are defined.
Reference
ƒ10 - Geopak On-line Manual.
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