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Calculating As Built Volumes

Updated November 30, 2017

This article applies to:
  • RoadEng Civil
  • RoadEng Forestry

In the Location module, cross section end areas (and therefore volumes) are calculated using a layer merging process which simulates the construction sequence. With fixed cross sections, you control the shape and order of the layers so it is important to understand this process.

  1. Layer 2 is compared with layer 1 (usually topo) and the difference is calculated; this defines the cut and fill areas for layer 2 (in this case stripping).

  2. Layers 1 and 2 are merged to create a new merged surface (in this case the stripped surface).

  3. The merged surface replaces layer 1, layer 3 replaces layer 2 and the two steps above are repeated.

  4. Repeat until all layers are processed.

The figure below shows the progression of the merged surface.

Merged surface
after Stripping is applied
Merged surface
after sub-cut is applied
Merged surface
after final is applied

Figure 1: Depiction of Merged Surface Progression

Note: The order of the layers in the Section Editor Tree-control is very important. Cut fill volumes are calculated between the current layer and the merged surface.