Add a free spiral-curve-spiral group between two entities.
The type of spirals created (simple vs. compound) depends on the types of entities you attach it to. When the attachment entities (1, 2) are edited, the spiral lengths (3, 4) and curve radius (5) do not change. The attachment points and the curve length adjust to accommodate edits to the attachment entities.
The Spiral-Curve-Spiral command is similar to the command that adds a free curve by radius between two entities. However, this command adds a transition spiral in and a transition spiral out. The curve group for this command is the same as the automatic curve group that is created when you use the Tangent-Tangent command. However, with this command you can create an SCS curve group between curves.
You cannot grip edit the spiral-curve-spiral curve group, but you can edit the entities to which the SCS group is attached. Make edits to the spiral or curve parameters in the Alignment Layout Parameters dialog box or the Alignment Entities vista.
SCS curve group between two tangents
An SCS curve group placed between two tangents creates two simple spirals.
SCS curve group between a curve and a tangent
An SCS curve group placed between a tangent and a curve results in the simple spiral attached to the tangent and a compound spiral attached to the curve.
SCS curve group between two curves
An SCS curve group placed between two curves creates two compound spirals. The SCS curve group should only be placed in a configuration where the attachment to either curve forms a compound curve-curve situation.
To add a free spiral-curve-spiral (between two entities)
- Click the alignment. Click Alignment tab
Modify panelGeometry Editor
. - On the Alignment Layout Tools toolbar, click
Free Spiral-Curve-Spiral (Between Two Entities). - Select the entity from which you want to add the spiral-curve-spiral.
- Select the entity to which you want to add the spiral-curve-spiral.
- Select the spiral-in length by picking two points in the drawing or by entering a spiral-in A value.
Specify a new value, or press Enter to accept the value that is displayed on the command line.
- If the alignment has design criteria applied to it, the minimum value for the current design speed is displayed.
- If the alignment does not have design criteria applied to it, the default value specified in the curve and spiral settings is displayed. For more information, see Curve and Spiral Settings.
- Select the spiral-out length or enter a spiral-out A value.
- Specify whether the curve solution angle is either greater than or less than 180 degrees.
- Specify a radius by either entering value or selecting two points in the drawing. Or, enter D to specify the degree of curvature
To display a curve preview you must either pick a point in the drawing or enter a coordinate value. Then, rubber band is drawn to the cursor from the selected point and the curve preview is displayed.
NoteTo calculate the radius or degree of curvature using other known curve parameters, enter 'CCALC to open the Curve Calculator. For more information, see Calculating Curve Parameters.