Horizontal Curve Table Items
The following items are available for display in the Horizontal Curve Table (see Curve Table Options dialog for more information).
Radius
Direction
Clock Wise = CW (right) or Counter Clock Wise = CCW (left)
Deg. of Curve - Arc (Da)
This item is the degree of curve, arc definition (a measure of curvature that depends only on radius). It is defined as the angle subtended by a curve with the same radius but with a specified arc length. The arc length is most often 100 project units (meters or feet). The arc length can be user defined in the Curve Table Options dialog as Stationing Distance.
Deg. of Curve - Chord (Dc)
This item is the degree of curve, chord definition (a measure of curvature that depends only on radius). It is defined as the angle subtended by a curve with the same radius but with a specified chord length. The chord length is most often 100 project units (meters or feet). The chord length can be user defined in the Curve Table Options dialog as Stationing Distance.
Arc Len. (L)
Chord Len. (C)
Angle (I)
This is the interior angle of the curve. It is defined as the angle subtended by vectors from the center to the BC point, and from the center to the EC point. See Curve Table Diagram.
Tangent (T)
Sometimes called sub-tangent, this is the length of the tangent line from the BC (or EC) point to the IP point. See Curve Table Diagram.
E. Distance (E)
This item is the external distance and is defined as the distance from the midpoint of the arc to the IP point. See Curve Table Diagram.
M. Ord (M)
This item is the middle ordinate and is defined as the distance from the midpoint of the chord to the midpoint of the arc. See Curve Table Diagram.
IPStn
IP (tangent Intersection Point) station measure. The IP station is calculated by adding the Tangent length to the BC Station; it is NOT the number half way between BC and EC stations.
IP X, Y
IP (tangent Intersection Point) coordinates.
BC Stn
BC (Begin Curve) station in L-line coordinates. In a spiral curve, this is the TS (Tangent to Spiral) point.
BC X, Y
BC coordinates.
EC Stn
EC (End Curve) station in L-line coordinates. In a spiral curve, this is the ST (Spiral to Tangent) point.
EC X, Y
EC coordinates.
Center X, Y
Circular curve center point coordinates.
Back Tan.
This item is the azimuth of the tangent line from the BC point to the IP point. The format of this angle can be changed by modifying the Direction setting on the Location Setup Units Tab.
Fore Tan.
This item is the azimuth of the tangent line from the IP point to the EC point. The format of this angle can be changed by modifying the Direction setting on the Location Setup Units Tab.
Chord Az.
This item is the azimuth of the line from the BC point to the EC point. The format of this angle can be changed by modifying the Direction setting on the Location Setup Units Tab.
Trans. Len. BC, EC
Desired transition length for super-elevation runoff and curve widening (actual transition can depend on nearby curves). For a spiral curve, this is the exact length of the spiral segment.
SC Stn.
Station of Spiral to Circle (SC) transition point.
SC X, Y.
Coordinates of Spiral to Circle (SC) transition point.
CS Stn.
Station of Circle to Spiral (CS) transition point.
CS X, Y.
Coordinates of Circle to Spiral (CS) transition point.
Design Speed.
Design Speed for this curve.
Super Elev. (e).
Super-elevation (%) between transition zones (maximum super-elevation for this curve).
BC R-Out.
Station for start of tangent run-out transition entering the curve. This should be the last cross section showing normal crown un-influenced by curve super-elevation.
Note that this point may not exist if there are nearby curves and transition zones overlap.
BC R-Off.
Station for start of super-elevation runoff (and curve widening) transition entering the curve. This cross section should show zero cross fall on the outside of the curve and normal crown on the inside.
This is always the TS point for spiral curves.
Note that this point may not exist if there are nearby curves and transition zones overlap.
BC F-Super.
Station for start of full super-elevation (and curve widening) section entering the curve. This station is the BC R-Off station + Transition Length.
This is always the SC point for spiral curves.
EC F-Super.
Station for end of full super-elevation (and curve widening) section leaving the curve. This station is the EC R-Off station - Transition Length.
This is always the CS point for spiral curves.
EC R-Off.
Station for end of super-elevation runoff (and curve widening) transition leaving the curve. This cross section should show zero cross fall on the outside of the curve and normal crown on the inside.
This is always the ST point for spiral curves.
Note that this point may not exist if there are nearby curves and transition zones overlap.
EC R-Out.
Station for end of tangent run-out transition leaving the curve. This should be the fisrt cross section showing normal crown un-influenced by curve super-elevation.
Note that this point may not exist if there are nearby curves and transition zones overlap.
