Civil 3D: Expressing Curve Delta (General vs Parcel)

August 24, 2021 Leo Lavayen

Fun fact: When labeling Parcels or Alignment segments, Civil 3D has a shared option for label styles.  It can pull from Parcel/Alignment or General collection for label styles.

The focus of this post will be on the ability to label a Curve Delta value using General labels similar to Parcel labels.



General Curve type labels (show as RED below) do not have a DELTA option for content selection from the Properties in the Text Component Editor window.  Parcel Curve labels (shown in BLUE below) do have a DELTA field default as a selection in the Properties drop down.


General Curve Label

Parcel Curve Label



Create a custom delta angle label.  As defined in the Civil 3D help file the Delta Angle (D) is expressed mathematically as the turned angle from the incoming tangent to the outgoing tangent line.

The calculations are created from the Toolspace > Settings tab > General collection > Label Styles > Curve > right click Expressions > select New

Named here as “Delta” built by subtracting the End Direction from the Start Direction to an Absolute Value to drop any negative signs, and setting format to an Angle.  
The Expression is simple:  
     ABS({General Segment Start Direction}-{General Segment End Direction})

Once the expression is created, it will be listed in the Text Component Editor list.  Custom expressions are typically placed at the top of the list and inserted like any other field.

When used, you can now see how the General label shown in RED and the Parcel label shown in BLUE both are labeling the Delta Angle with matching values on the same curve.

This is one example of how custom Expressions can be used to show data that Civil 3D knows in a label.

About the Author

Leo Lavayen

Civil Applications Expert<br><br>As an Applications Expert, Leo is responsible for supporting, training and implementation of software for survey and civil engineering professionals. He has more than 19 years of experience helping large and small, public and private clients in the eastern United States.

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