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1. Sectional volume methods

The following information is extracted from Autodesk Civil 3D help document at:

https://help.autodesk.com/view/CIV3D/2025/ENU/?guid=GUID-1E3A9CD9-DFD6-4455-9EB1-D8E46721A0B4

Civil 3D support three different volume calculation methods: 

1. Average End Area

2. Prismoidal

3. Composite

Scope of application:

• If the cut/fill areas between two successive stations are of similar shape, then the Average End Area Method can be used.

• If the terrain has greater changes between stations, then the Prismoidal Method can be more accurate.

• The Composite Method uses the actual surface data and does not use formulas to interpolate the volume between sample lines.  This method is particularly useful if the any of the surface triangle edges are smaller than the sample line interval.

2. Sectional length quantity

Civil 3D can report cross-sectional area and the incremental volume between 2 successive cross-section

However, Civil 3D CANNOT report segment length or link length,  therefore the area S between successive sample lines is not available.

3. Sectional Volumes Across Multiple Baselines

As stated in this link:

https://help.autodesk.com/view/CIV3D/2025/ENU/?guid=GUID-16E7E288-EC19-4535-BF3D-59F029C8BE56

"You can include multiple baselines in a corridor volume calculation, but you should make sure that the assumptions for the volume calculation method are satisfied. That is, the distance (L) must be accurate for all baselines."  

(L is the distance along baseline alignment between 2 successive sample line)

In other words, Sampling Sectional Volumes Across Multiple Baselines are feasible when all baselines (alignments) must be parallel so that:

• Sample lines are perpendicular to all alignments, and

• Distance L between 2 successive sample lines is the same for all alignments

In fact, above condition is rarely met.  When the condition is met, it is better to build a single corridor with one alignment and a combined assembly instead of  multi parallel alignments and separated assembly.

For more information, please refer to the next article:  P04: Material List