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Merging Terrains

Updated November 15, 2017


This article applies to:
  • RoadEng Civil
  • RoadEng Forestry

Next the designed surface created above will be merged with the original ground terrain to make a composite.

  1. Open the Terrain module (the Location module menu Setup | Terrain button is handy).

  2. File | Open <RoadEngCivil>\Location\Topo.terx.

  3. The first step is to save this file to a new location so the location design is not ruined by modifying the original ground terrain.

  4. Use File | Save As to open the file save dialogue box.

    1. Ensure file type is set to Softree-Terrain File (*.terx).

    2. Change folders to <RoadEngCivil>\Composite.

    3. Name the output file Composite Surface xx, where xx are your initials (this will prevent writing over the example file).

    4. Press Save button to copy the file.

  5. Bring in file from previous exercise: Terrain Modeling | Merge Terrain button. This will open the Merge Surface Dialogue box (below).

  6. Browse… for <RoadEngCivil>\Composite\Road Surface XXX.terx (the file you created in the previous exercise).

Figure 1: Merge Surface Dialogue Box

  1. Press OK to merge the Terrains. A “Warning No Space for Undo” appears. Say OK to continue.

Figure 2: Warning Dialogue Box

  1. Now we need to re-calculate the surface. Terrain Modeling | Generate TIN button. This will open the Terrain Calculation Dialogue box.

  2. Keep the existing settings and press OK to recalculate the triangles and contours.

  3. View |New Window Button |select 3D from drop down menu. A 3D window will appear on your screen.

  4. View | Tile Vertically Button to see the 3D and Plan windows side by side.

  5. File | New do not save changes.

Figure 3: Composite Surface Showing Designed
Road Merged with Original Ground.

Iterative Alignment Design

This composite surface model could now be used as the original ground surface for a new Location design. This could be used to design an intersecting road, driveway or overpass. This would ensure grade elevations are coincident (or grade separation in the case of an overpass) and would avoid any double counting of volumes. We might also wish to design the other direction for a divided highway.

Figure 25‑7: 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 25‑8: 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 4: 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 5: 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 6: 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.

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