
Reference Information
This command defines new curve sets and modifies existing curve sets in the active horizontal alignment.
The accepted solution is displayed in the drawing file.
Dialog Box Options
Horizontal PI
By default, the text fields in the Horizontal PI group box are populated with values that describe the position of the current PI relative to the previous and next PIs. However, when you change those numeric values and then click Apply, you are redefining the location of the PI.
For example, assume that Define By is set to Directions from Previous and Next PIs and that you have modified the values of the Direction Back and Direction Ahead. When you click Apply, the PI is repositioned based on the intersection of those directions projected from the previous and next PIs.
Define By
specifies the method by which the location of the PI is determined. The choices describe five combinations of parameters sufficient to locate a PI in the horizontal alignment:
Known PI Coordinates
Direction and Distance from Previous PI
Direction and Distance from Next PI
Directions from Previous and Next PIs
Distances from Previous and Next PIs
Direction Back
specifies the direction of the back tangent.
Length Back
specifies the length of the back tangent.
Point Name
displays the name of a point on the back tangent.
Northing
specifies the northing coordinate of a point on the back tangent.
Easting
specifies the easting coordinate of a point on the back tangent.
Direction Ahead
specifies the direction of the ahead tangent.
Length Ahead
specifies the length of the ahead tangent.
Horizontal Curve
Curve Set Type
indicates whether to define a spiralcurvespiral (SCS) combination or a spiralcurvespiralcurvespiral (SCSCS) combination.
Define Transitions By
specifies whether curve transitions are defined by length or by spiral constant. The default value for this parameter is set on the Geometry tab under Tools > Options.
Length
specifies that the Leading Transition, Compound Transition, and Trailing Transition keyin fields define transition length.
Constant
specifies that the Leading Transition, Compound Transition, and Trailing Transition keyin fields each define a spiral constant for the transition.
Leading Transition
defines the incoming spiral for the curve set. Choose from the following curve definitions: Clothoid, Cubic Parabola, Biquadratic Parabola, Bloss, Sinusoid, and Cosine. Depending on the setting of Define Transitions By, key in either the transition length or the spiral constant.
The following choices are available only in Bentley Rail Track: Cubic Parabola, Biquadratic Parabola, Bloss, Sinusoid, and Cosine.
Radius 1
specifies the radius of the horizontal curve.
Compound Transition
defines the middle spiral in an SCSCS curve set (when the Curve Set Type is SCSCS). Choose from the following curve definitions: Clothoid, Cubic Parabola, Biquadratic Parabola, Bloss, Sinusoid, and Cosine. Depending on the setting of Define Transitions By, key in either the transition length or the spiral constant.
The following choices are available only in Bentley Rail Track: Cubic Parabola, Biquadratic Parabola, Bloss, Sinusoid, and Cosine
Radius 2
specifies the radius of the second horizontal curve in an SCSCS curve set (when the Curve Set Type is SCSCS).
Trailing Transition
defines the outgoing spiral for the curve set. Choose from the following curve definitions: Clothoid, Cubic Parabola, Biquadratic Parabola, Bloss, Sinusoid, and Cosine. Depending on the setting of Define Transitions By, key in either the transition length or the spiral constant.
The following choices are available only in Bentley Rail Track: Cubic Parabola, Biquadratic Parabola, Bloss, Sinusoid, and Cosine.
Define By
specifies a known point through which the curve set passes.
Radius
specifies the known radius of the curve set.
Tangent to Spiral
specifies the known beginning of the curve set.
Spiral to Tangent
specifies the known ending of the curve set.
Point on Curve
specifies the known as a point on the circular curve.
Angle up to PCC (PC to PCC)
specifies the central angle from the shifted PC to the PCC.
Angle after PCC (PCC to PT)
specifies the central angle from the PCC to the shifted PT.
Angle Text Field and Data Point Button
allows you to enter the central angle.
Point Name
specifies the name of the known point.
Northing
specifies the northing coordinate of the known point.
Easting
specifies the easting coordinate of the known point.
Apply
initiates the command using the information defined in the dialog box. The dialog box will remain active after you click Apply.
Close
dismisses the dialog box and exits the command. The information you entered in the dialog box will be displayed the next time you use this command.
Undo
undoes the last Apply and resets the edited entry fields to the previous values.
Rate Calc
displays the Superelevation Rate Calculator Editor dialog box.
Design Calc
activates the Design Calculators dialog box.
The Design Calc button is disabled in the following products: InRoads Storm & Sanitary, InRoads Bridge, InRoads Site, and InRoads Survey.
Curve Calc
displays the Curve Calculator dialog box.
When performing calculations, the software uses the arc definition of the alignment. 
Report
displays the Results dialog box. A Ctrl+Report displays the entire alignment rather than the active curve set.
Help
displays help.
First
edits the parameters that define the first curve on the horizontal alignment.
<Previous
edits the parameters that define the curve previous to the current curve set.
Next>
edits the parameters that define the curve that follows the current curve set.
Last
edits the parameters that define the last curve on the horizontal alignment.
Select
allows you to select a horizontal curve set by identifying the curve in graphics.