# Earthworks Fill Area Calculations in TBC

Just wondering if there is an easy way to slice a design surface with varying slopes by lift layers for the purpose of area computations in TBC.

I would like to put a slice through a design surface at say 300mm, 600mm etc… below the design surface to create a string that can then be used to compute the area of the relevant earthworks lift, including the fill batter area.

Case in point here is when a grader is working with a design file and is putting in an earthworks lift at an elevation below the design. When the grader grades out to daylight, we would like to be able to compute this in TBC.

Peter

If you have the 3D strings for Finished grade you can do this with the Slope Slope Intersection calculator - eg for a Berm, Dam or Embankment or road project

Slope 1 is between string 1 and 2
Slope 2 is between string 3 and 4
Enter your vertical offsets (300mm) / perpendicular offsets
It projects slope 1 at the elevation delta to slope 2 at its elevation delta and finds you the intersection string as well as all the offset strings for each of the 4 strings - you can make surfaces or polygons out of those to get the grading areas

You can also do the following

Create a Datum Surface (a big rectangle that covers the entire site at each elevation that you want to slice) and then run the Rockpile Create Surface Intersection command to find out where the datum intersects the design model surface - if you have areas where the surface will not intersect, I normally create a surface edge breakline around the design surface and then Offset it e.g 0.1m and vertically by say -50m to create a vertical face around the model that can be intersected by the datum planes - that way if it intersects one side of the surface but not the other it will draw you a line along the edge of the model when you use the Surface Intersection linestring command.

Hope that this helps - call my cell if you need to discuss

Alan