Calculation of earthwork volumes involves the following steps:
1. L-line cross sections are calculated at each point (reporting, grade and plan) on the L-line. These L-line cross sections are created by translating and projecting the nearest P-line cross section. The offset from the P-line and the difference in angles between the P-line cross section and the L-line cross section are required. The following figure illustrates the procedure for determination of L-line cross sections.
Figure 1. L-line cross sections
2. If overburden stripping has been selected, then the stripping material is removed.
3. Intersection of the template with the L-line section is calculated using the various slope angles, ditch configuration etc.
4. Fill and cut cross sectional areas (for each stratum layer) are calculated. These areas are exact i.e. no gridding or numerical approximations are made. Cut areas are multiplied by the cut expansion factor for the layer material type. The fill area is multiplied by the fill expansion factor for the fill material type (see Expansion and Compaction for details).
5. The volume between two stations (on the L-line) is calculated by taking the average of the areas at each station and multiplying by the distance between (difference in L-line stations). This method is known as the "Average End Area Technique".
