Estimating Cut and Fill Construction Projects By-Hand

Overview

There are two basic methods for calculating cut and fill construction projects by hand.

The first is called the grid method. In the grid method, you divide your plan up into a set at equally sized grid squares and then determine the cut or fill volume for each individual grid cell. The total cut and fill for the site is then just the sum of all of the cuts and all of the fills for the individual grid cells. Expect to spend about 6 to 8 hours to complete your take of a single sheet when using the grid method with accuracy of around +/-20%

The second is call the cross-section method. The cross-section method, you drawing equally spaced horizontal lines across your plan and then for each line draw graph of the existing and proposed services along that line. You then determine your cut area and fill area for each of those cross-section lines. And then you calculate your cut and fill volumes by averaging the cut areas and fill areas between each adjacent cross-sections the multiplying by the distance between to get the volume. Expect to spend about 8 to 10 hours to complete your take off of the single sheet when using the cross-section method with accuracy of around +/-15%.

 

The Grid Method

To use the grid method to calculate your cut and fill construction projects, do the following steps:

  1. Lay your plan out on the flat surface. Then with a large T-square, draw set of equally spaced horizontal and vertical lines across your plan.
  2. At each intersection of the horizontal and vertical lines, determine the existing and the proposed elevation
  3. For each intersection subtract the existing elevation from the proposed elevation. Positive numbers are fill. Negative numbers are cut.
  4. For each cell, add the four cut and fill numbers together and divide them by 4.0 to calculate the average cut or fill depth for that cell.
  5. Multiply the average cut or fill depth by the number of square feet in the grid cell to get the cut or fill volume in cubic feet.
  6. Add all of the cut volumes up and divide that number by 27 to get the total cut for the site in cubic yards.
  7. Add all of the fill volumes up and divide that number by 27 to get the total fill for the site in cubic yards.
  8. To calculate the import or export, subtract the fill volume from the cut volume. If the result is a positive number, you have more cut than fill and you will need export material from your site. If the numbers negative, you will need to import dirt onto the building site.

 

The Cross-section Method

To use the cross-section method to calculate your cut and fill construction project, do the following:

  1. Lay your plan out on a smooth level service, and with a T-square, divide your plan with a number of equally spaced horizontal lines.
  2. On a piece of graph paper, preferably 11 x 17”, plot out the existing elevations from the beginning to the end of each cross-section line. The vertical axis is for elevations and the horizontal axis is for the distance along the cross-section.
  3. Then for each cross-section, plot out the proposed elevations from the beginning to the end of each cross-section line on the same graph as the existing.
  4. For each cross-section, count the number of squares where the existing line is above the proposed line. This is your cut area for that cross-section.
  5. For each cross-section, cout the number of squares where the existing line is below the proposed line. This is your fill area for that cross-section.
  6. For each adjacent pair of cross-sections, average the cut area between the two and multiply it by the distance between the two cross-sections to calculate your cut volume.
  7. For each adjacent pair of cross-sections, average the fill area between the two and multiply by the distance between the two cross-sections to calculate your fill volume
  8. Now add up all of your cut volumes and divide them by 27 to get the total cut volume for your site in cubic yards.
  9. Add up all of your fill volumes and divide them by 27 to get the total fill volume for your site in cubic yards.
  10. To determine the export for your site, subtract the fill volume from the cut volume. If this is a positive number, then you have more cut than fill so you’ll need to export material from your site. If the numbers negative you have more fill than cut, and you will need to import material onto your building site.

 

Conclusion

The advantage of both of these methods is of they are very inexpensive to do. Anyone with the proper training can do about one take off a day using either of these methods.

The disadvantage of both of these methods is of they require a full day to do a take off and their accuracy is typically between ± 15% to 20%.

So if you’re interested in increasing your bidding speed and accuracy, then fill out the form on the right sidebar to request a trial of the earthworks excavation software today!