Method of quantity estimate for road

Quantities of road earthwork are found from the longitudinal section and cross-sections.

1. Take cross-sections at regular intervals (e.g. 10–30 m, closer on curves) and at points where the ground changes.
2. Find the depth of cutting or height of filling at the centre line from the ground level and formation level; the formation level follows the design gradients.
3. For each section calculate the area of cutting and filling from the formation width and side slopes ($A = (B + s h)h$ for level ground; side-hill formulae when the ground has a cross slope).
4. Find the volume between consecutive sections by the mean sectional area method ($V = \tfrac{A_1 + A_2}{2} \times L$), or the prismoidal formula for greater accuracy.
5. Add the quantities of pavement layers (area × thickness), drains, culverts and protection works, and put everything in a bill of quantities.