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Creating Surfaces for Pay Quantities

Updated November 30, 2017

This article applies to:
  • RoadEng Civil

This example we will calculate sub-cut pay quantities where the sub-cut material must be below both stripping (WG) and sub-grade (SG). To do this calculation we will automatically create a new surface (SCTop: sub-cut top) which runs along the top of the sub-cut. The SCTop surface is the minimum of WG and SG.

Figure 1: Top of Sub-Cut Surface

We start by opening an existing design file created from an as-built survey.

  1. Start the Location module. File | Open <RoadEngCivil>\As-Built\PartE.dsnx.

Figure 25‑35: Design Created From an As-Built Survey, with Fixed Sections.

  1. In the Section Editor tree-control, select station 13740 | press the Layer Operations… button to open the Layer Operations dialogue box shown below.

Figure 25‑36: Layer Operations Dialogue

  1. Set the parameters as shown in the figure above.

  2. When you press OK, these parameters will create a new surface (SCTop) which is the minimum (in elevation) of WG and FG. This process is applied to all cross sections. The Horizontal Extents of the new surface will not extend outside layer UG. SCTop will exist anywhere either WG or FG exist (union).

  3. The next step will shift the new SCTop surface so that it is processed after WG and before SC. The new processing order will be:

Topo original ground
WG stripping
SCTop sub grade (above sub-cut)
UC Sub-cut
FG Sub-grade (outside sub-cut)

Cut and fill volumes are calculated after each step and a new merged surface is created (see Part C: Volume Calculations).

  1. In the Section Editor tree-control, select station 13740 and press the button to expand the tree (if necessary).

  1. Select the new SCTop layer (it should be at the bottom).

  2. Press the Shift Up button until SCTop is between WG and UC.

  3. Press the Apply to all Sections button to update the order on the other sections.

  1. If you look closely at the cross section one can see the that the undercut layer crosses the stripped surface. This is technically not possible there must have been an error in the survey. The next step will remove any of the UC layer which extends above WG or FG (figure below). Sub-cut (UC) should never fill.

Figure 2: Before (left) and After (right) Trimming (step below).

  1. In the Section Editor tree-control, select station 13740 and press the Layer Operations… button to activate the Layer Operations dialogue. Set the parameters as shown in the figure below.

Figure 3: Trimming UC above WG or FG

  1. Press OK and answer OK when prompted to overwrite layer UC.

  2. With the mouse in the sub cut area in the cross section, right click and select Hatch Cut Area for UC.

Figure 4: Sub-Cut Area

  1. The data report now accurately shows the pay volume for under-cut under sub-grade.

  2. File | Close. Do not save changes.