To Create User-defined Curves

Create a user-defined curve by selecting a single alignment element or string of adjacent alignment elements.

Use this command to handle special geometric cases where a curve is not automatically created by Autodesk Civil 3D, for example where an alignment has two compound spirals or a compound spiral in between spirals. If there is no geometry available for the user-defined curve, you are prompted to press Enter to exit the command.

Note: If an alignment does not contain curves, you may select straights as the elements to which to apply superelevation data.

1. Click an alignment in the drawing.
2. Click Alignment tabModify panelSuperelevation drop-downCalculate/Edit Superelevation Find.
   Note: The first time you use the Calculate/Edit Superelevation command on an alignment that contains no superelevation data, a superelevation curve is calculated for each curve (circular arc) in the alignment. A task dialog is displayed with the following options:

   • Calculate Superelevation Now - choose this option to launch the Superelevation Calculation wizard.
   • Open The Superelevation Curve Manager - choose this option to open the Superelevation Curve Manager, where you can view curve data.

     After the initial superelevation calculation, the Calculate/Edit Superelevation command automatically displays the Superelevation Curve Manager.

3. In the task dialog box, click Open The Superelevation Curve Manager.
4. Click Create User-defined Curve.

   At the command line you are prompted to select the starting element for the superelevation curve group.

   Note: If an alignment does not contain curves, you may select straights as the elements to which to apply superelevation data.
5. In the drawing, select the starting element and the ending element for the superelevation curve group.

   The user-defined curve is displayed in the Superelevation Curve Manager dialog box and the status is “Not Calculated”.

6. Click Superelevation Wizard.
7. In the Create Superelevation dialog box, select This Curve Only.
8. Click OK and complete the Superelevation wizard.