In the cross-section method, how is volume determined?

• A. By measuring the cross sections and averaging them.
• B. By multiplying the average cross-sectional area by the spacing.
• C. By summing the end areas from all sections.
• D. By summing the volumes between successive cross sections.

Answer: (D)

In this method, you determine volume by breaking the project into slices between consecutive cross-sections and adding up those volumes. For each adjacent pair of sections, you estimate the segment’s volume as the average of the two cross-sectional areas multiplied by the spacing between the sections (a trapezoidal approximation). By summing these segment volumes along all intervals, you obtain the total earthwork volume. This additive approach reflects how volume accumulates along the alignment, and it matches how the cross-sectional areas change from one station to the next.