Curve Calculator Dialog Box

Use this dialog box to calculate curve parameters from input.

Note: To change the units used in the Curve Calculator dialog box, use the Ambient Settings tab of the Drawing Settings dialog box. Under Angle, change the Format value to the unit you want to use. For more information, see To Specify Ambient Settings.

The following illustration shows the curve parameters used by Autodesk Civil 3D

Degree Of Curvature Definition

Specifies whether the degree of curvature will be based on the arc or the chord.

• Chord Definition: Specifies that the degree of curvature is determined by the chord. Use this option if the curve is a railway curve. For a railway curve, the degree of curvature is the angle at the center of a circular curve subtended by a chord of 100 units.
• Arc Definition: Specifies that the degree of curvature is determined by the arc. Use this option if the curve is a roadway curve. For a roadway curve, the degree of curve is the central angle subtended by a circular arc of 100 units.

The following illustration shows the degree of curve definition for arcs and chords.

Fixed Property

Specifies which property to hold as fixed while performing calculations.

• Radius: Specifies that the radius will be fixed.
• Delta Angle: Specifies that the delta angle will be fixed.

Degree Of Curvature

Specifies the degree of curvature.

Delta Angle

Specifies the delta angle of the curve. This option is not adjustible if Delta Angle is specified as the Fixed Property.

Radius

Specifies the radius of the curve. This option is not adjustible if Radius is specified as the Fixed Property.

Tangent Distance

Specifies the tangent length of the curve.

Arc Distance

Specifies the arc length of the curve.

Chord Distance

Specifies the chord length of the curve.

External Distance

Specifies the external secant length of the curve.

Mid-ordinate Distance

Specifies the mid-ordinate length of the curve.

Sends the current value to the command line.

Optionally selects an arc in the drawing and displays its values in the calculator. No edits you subsequently make in the calculator are updated in the drawing.