Calculating Earthwork Quantities between two surfaces

Earthwork  estimation is an important part of any civil engineering project. Civil3D provides you with a streamlined method to calculate total cut, fill and net volumes of earthwork between the existing and the desired surface. The earthwork volumes between two surfaces can be calculated either by creating volume surface or by directly calculating the total cut and fill volumes between the two surfaces.

Civil 3D is the most powerful, simple and accurate tool to make earthwork calculations. For earthwork calculations you just need two surfaces in your drawing, one is the existing surface and other is the desired surface. Civil 3D analyzes both the surfaces and calculates the total volume of cut and fill by comparing the vertical distance between points in these surfaces. The distance between the elevations of two surfaces can then be used to create a third surface, known as volume surface. The most efficient method to calculate Earthwork quantities through Civil3D is  by using Composite Volumes.

To use Composite Volumes, type reportsurfacevolume in the command line and press ENTER . On doing so, Panorama window with the Composite Volumes tab will be displayed.

The following tutorial will explain the whole procedure to calculate the Earthwork Quantities using Composite Volume method and how to create a TIN volume Surface .

1.  Before starting the tutorial download the c04_civil_3d_2014_tut.zip file from www.cadcim.com. The path of the file is as follows: Textbooks > Civil/GIS > AutoCAD Civil 3D > Exploring AutoCAD Civil 3D 2014.

2.Save and extract the downloaded file at the following location:

C:\civil3d_2014\c04

3. Open the File civil3d_2014_c04_tut01

The drawing file consists of two TIN surfaces: the Existing Ground surface with borders and contours, and the Proposed Ground surface with triangles. You will notice a magenta colored polygon in the Proposed Ground surface.

Computing Composite Volumes

1. Enter REPORTSURFACEVOLUME at the command prompt; the Composite Volumes tab in the Panorama window is displayed.

2. Choose the Create new volume entry button from the Composite Volumes tab of the Panorama window; a new volume entry is added to the list box.

3. Double-click on the cell in the Base Surface column; a drop-down list is displayed. Select the Existing Ground option from this drop-down list

4. Similarly, select the Proposed Ground option from the drop-down list in the Comparison Surface column. On specifying the base and comparison surfaces, the net cut and fill volumes are displayed in the Cut and Fill columns, respectively.

The total volume of material to be removed from the existing ground is 20567.26 Cu.Yd. and the total material required to be filled is 13341.22 Cu Yd.

5. Accept the default cut and fill factor values. Move the slider at the bottom of the Panorama window to pan across the window to view the adjusted values for the cut, fill and net material required. The net volume of material is 7226-05 Cu Yd. This means that to create a balanced proposed ground, the 7226-05 Cu Yd of material needs to be removed from the existing ground. Note that the red graph in the Net Graph column indicates that the material needs to be removed from the base surface.

6. Close the Panorama window.

Creating the TIN Volume Surface

1. Choose the Create Surface tool from Home > Create Ground Data > Surfaces drop-down; the Create Surface dialog box is displayed.

2. In this dialog box, select the TIN volume surface option from the Type drop-down list.

3. Set the values of the TIN volume surface properties as follows:

 Name: Volume Surface             Base Surface: Existing Ground

Comparison Surface: Proposed Ground

4. Choose the OK button; the Create Surface dialog box is closed. The surface is created and displayed in different colored bands.