Ground Design Difference Grid

Calculate a grid and height difference between two surfaces.

This function allows you to grid, and obtains the difference between, a "design" surface and "ground" surface.

General details are the same as those described for the Ground/Design Surface DTM. Volume details are the same as those described in the Ground/Design Surface option.

In this function, the grid points are generated only in areas where there is both ground and design data.

The grid elevations that are retained are the differences in elevation between the two surfaces.

This type of grid model is extremely useful in showing depths of cut and fill. These contours are widely used to check designs, control site earthworks and obtain "as built" data. Due to their flexibility, these isopachyte contours largely replace the traditional mass haul diagram for planning and executing bulk earthworks and dredging.

You should read the general discussion on DTM Volumes.

Procedure

1. The DTM Grid Volumes - Grid Type page displays.

2. Select the Ground/design difference and click Next.

3. The DTM Grid Volumes - Surface Details page displays.

4. Select the relevant surfaces and click Next to continue.

5. The DTM Grid Volumes - Grid Details page displays.

6. Fill in the relevant data and click Next to continue.

7. The DTM Grid Volumes - Search Distances page displays.

8. Fill in the relevant data and click Finish to continue.

9. The results display in the Output Bar.

10. The Topsoil Stripping and Compaction options display so you can change the topsoil and compaction factor parameters, if required.

11. Fill in the relevant data and click Calculate to continue; or Finish to update the totals and end the function.