# Define Vertical Curve Set

This command modifies a curve on the active vertical alignment. You can also place a curve between two tangents with this command.

Before Using This Command

• You must have an active project, active horizontal alignment, and active vertical alignment. The horizontal alignment can be empty.

• You must first place a profile window in the drawing file.

Dialog Box Options

Vertical PI

By default, the text fields in the Vertical 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 PVI By is set to Entrance and Exit Grades and that you have modified the values of the Entrance Grade and Exit Grade. When you click Apply, the PI is repositioned based on the intersection of those grades projected from the previous and next PIs.

Define PVI By

specifies the method by which the location of the PVI is determined. The choices describe four combinations of parameters sufficient to locate a vertical PI in the vertical alignment:

• Station and Elevation

Station

defines the station value of the PI.

Elevation

defines the elevation of the vertical PI.

defines the grade from the previous PI to the current PI.

defines the grade from the current PI to the next PI.

Vertical Curve

Calculate By

specifies the method used for recalculating the curve length. The options for parabolic alignments are:

• Length of Curve - specifies the length of the vertical curve.

• r=(g2-g1)/L - specifies the rate of change.

• Middle Ordinate - specifies the middle ordinate or external distance.

• Pass-through - specifies the pass-through point by station and elevation.

• K=L/(g2-g1) - specifies the vertical curves K.

• Unsymmetrical Length - specifies the length from the PVC to the PVI and the distance from the PVI to the PVC.

The options for circular vertical alignments are:

• Pass-through - specifies the pass-through point by station and elevation.

• Tangent - specifies the tangent of the element.

(parameter 1)

this parameter varies depending on the Calculate By method selected.

(parameter 2)

this parameter varies depending on the Calculate By method selected.

The settings in the Adjacent Curves group box are relevant when you make an edit that affects the adjacent curves.

For example, changing the elevation of the current PVI would cause the following to be recomputed: exit grade of the previous curve, entrance and exit grade of the current curve, and entrance grade of the next curve. The previous curve would be recomputed by holding the original PVI station and elevation as well as the entrance grade. The exit grade would be recomputed. The next curve would be recomputed by holding the original PVI station and elevation as well as the exit grade. The entrance grade would be recomputed.

In adjacent curves, the length of curve is either preserved or recomputed, based on the setting of the Update By parameter.

Update By

specifies which parameter to preserve in recomputed adjacent curves. The specified parameter is preserved. The adjacent curves may be recomputed by Length of Curve, r=(g2-g1)/L, or K=L/(g2-g1).

If you select Length of Curve, the length of curve is preserved and the software recomputes the curve. If you select r=(g2-g1)/L, the software recomputes the curve length based on the original rate of change. If you select K=L/(g2-g1), the software recomputes the curve length based on the original K.

In the case of either r=(g2-g1)/L or K=L/(g2-g1), the Distance parameter controls whether the computed length of curve is rounded. See the Distance parameter for more information.

Distance

rounds the recomputed length of vertical curves up or down to the nearest multiple of the value specified in the associated text field. The Distance parameter applies only when Update By is set to r=(g2-g1)/L or K=L/(g2-g1). A zero value (0.0) has no effect.

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.

Design Calc

displays the Vertical Design Calculator dialog box, which is used to compute a vertical curve based on a variety of design criteria.

The Design Calc button is disabled in the following products: InRoads Storm & Sanitary, InRoads Bridge, InRoads Site, and InRoads Survey. Furthermore, the Design Calc button is available only when the Curve Definition for the active vertical alignment is Parabolic. The Design Calculators dialog box is not available when the Curve Definition is set to Circular.

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 vertical alignment.

<Previous

edits the parameters that define the curve previous to the current vertical curve.

Next>

edits the parameters that define the curve that follows the current vertical curve.

Last

edits the parameters that define the last curve on the vertical alignment.

Select

allows you to select a vertical curve set by identifying the curve in a profile in graphics.