User Guide
User Guide
User Guide

Place Spiral

Use it!

Used to place a transitional spiral as a B-spline curve.

Tool SettingEffect
Type

Sets the spiral's mathematical definition.

  • Clothoid
    • — Used to create a smooth transition between arcs that have different radii so that there is no abrupt change of curvature. Used in highway design.
  • Archimedes
    • — The radius changes linearly based on the angle.
  • Logarithmic
    • — The radius changes exponentially based on the angle.
Initial Degree

(Type set to Clothoid only) Sets the degree of curvature at the origin.

Final Degree

(Type set to Clothoid only) Sets the degree of curvature at the spiral's endpoint.

Length

(Type set to Clothoid only) Sets the spiral's length.

Initial Radius

(Type set to Archimedes or Logarithmic only) Sets the radius at the origin.

Final Radius

(Type set to Archimedes or Logarithmic only) Sets the radius at the spiral's endpoint.

Angle

(Type set to Archimedes or Logarithmic only) Sets the sweep angle.

Tolerance

(Type set to Clothoid or Logarithmic only) Sets the tolerance.

To place a spiral
  1. Select the Place Spiral tool.

  2. Enter a data point to define the spiral's origin.

  3. Enter a data point to define the tangent direction at the origin.

  4. Enter a data point to define the spiral's direction.

Key-in: PLACE SPIRAL