Calculating Earthworks Cut & Fill With A Spreadsheet | Cross Section Method

The cross-section method is when you divide your site into equal parallel sections. Imagine slicing through the earth with a knife at regular intervals.

For each cross section the cut area and the fill area are calculated. Then for each cross section pair, the cut and fill volume of the section between them is approximated  by finding the average of two adjacent sections and multiplying by the distance between them.

USING A SPREADSHEET

As there are so many calculations to complete, another method is using a spreadsheet, such as the one we have provided.

The spreadsheet : 

a)  Creates a graph showing the profile of the Existing and Proposed for each section.  This shows the existing levels in blue and proposed in orange. 

b)  Calculates the cut and fill area for each section.  Shown next to the profile graph.

c)  Calculates the overall total Cut, Fill and Net Volume. Shown in the Results table.

COLLECTING CROSS SECTION DATA

1. Print a copy of your site plan with the existing and proposed levels defined.

2. Check the scale and units of your site plan.  You need to know the scale to calculate the length of you cross section, the distance between them and the distances along the cross section where the elevation changes. The photo opposite shows 4cm is the equivalent to 20m on the plan.

3. Draw your cross section lines. You can either hand draw it to match your requirements or draw in CAD.

Whichever method you decide, you do need to number the lines; 1-… however many you have. The spreadsheet has a maximum of 25 lines for you to enter data into. 

This example plan is in metric units (centimetres (cm) so we have used 2cm = 10m.  When you are deciding the distance between each section, it is important to consider that the shorter the distance, the more sections and data you will collect.  Therefore, the more accurate your end results and estimations will be. 

4. Collect your data.  You now need to take off the existing (E) and proposed (P) levels and write them next to each significant change in elevation, to produce a cross section.  An example, showing one way to do this, is in the photo. It is key to use your fine pen or pencil here to ensure you can fit in the two levels and so they remain legible.

In this example, the levels have been defined using contour lines.

i) For each contour make a mark on your section and write the level.  

I have used two colours to make the mark; black for existing and written the level above the section line and pink for the proposed and the level is written below the line.  This makes it clear for when you are entering the levels into the spreadsheet. 

ii) The start of the section is 0 distance and then you measure from 0 along the line to get the distance for the change in elevation.  The distances for the changes for the existing may well be different to the proposed. 

You can use a ruler to measure the distance in cm/mm/inches and then multiple by x to scale it.  Alternatively, you can use a scale ruler with a compatible level which means you don’t need to complete that sum – really handy! 

INPUTTING DATA INTO THE SPREADSHEET

1. Open the spreadsheet and select the “Section Method Example” tab so that you have the sheet on screen.

You will notice that this sheet is protected and cannot be amended. Before starting your own sheet, we recommend you view this example to understand what your finished cross section results should look like. 

2. Open the second tab called, “Section Method”.  This one you can edit and enter your data into. (Please refer to the licence tab for modifying and redistributing terms.)