Creating a Strata Surface Out Of Provided Contours for Rock

This question comes up from time to time

I have been provided with a CAD file of Contours that represent the engineers assumed top of rock surface. How can I use those contours to model the rock surface in Takeoff as a Strata surface?

The process is as follows

  1. Model your Original ground from the data on the layers categorized as Original.
  2. Model you Finished Grade from the data on the layers categorized as Design
  3. isolate the Rock Contours data so you can easily select it by layer
  4. Use the MSI Manager to create Earthen Materials for your strata materials e.g. below Original is Soil and below Rock is Rock.
  5. Use the Takeoff Define Strata command to define the Strata and Materials - Below Original say Soil and then create a second strata called Rock and below that select Rock. Make sure that you set the Rock Strata to be “Elevation” rather than “Depth” because your contours are Elevation Contours not Depth below Existing Contours.
  6. Use the Takeoff Build Surfaces command to build your surfaces.
  7. Use the Surfaces Menu - Add / Remove Surface Members command to add your Rock Contours to the Rock Surface
  8. If you build surfaces and the contours do not seem to elevate the Rock Surface then you will need to add a single Boring Log. The Takeoff Strata functions were all designed around Boring Logs so you need at least one to trigger the formation of the surface. Find any Rock Contour and make a note of its elevation. Use the Create Boring Log function to create a Boring Log - give it a Name e.g. BH1 and then put it on a layer e.g. SITE - Boring Logs. Now pick its location - click on the contour at a node so you get an accurate snap point. The Original Ground elevation will be determined at that point. Now enter the Boring Log Stratum Settings and enter the data using Elevation mode and enter the elevation of the contour you chose as the Elevation of the Rock Surface at that boring log point. Click OK to complete that Boring Log.
  9. Now use Build Surfaces again and the Strata Surface should now be created and have the correct elevation. Note the Strata Surface will be limited automatically to the extents of the existing ground model.
  10. Now run your Takeoff Reports and the Earthworks Cu should bow be split into Soil and Rock quantities as per your strata model.

Video Shows You How

Example Project

Here is the project file that I am using for this example
Takeoff From Strata Contours.vce (267.8 KB)