The cross-section method is employed almost exclusively for computing volumes
on linear construction projects such as highways, railroads, and canals. In this procedure,
after the centerline has been staked, ground profiles called cross sections
are taken (at right angles to the centerline), usually at intervals of full or half stations
if the English system of units is being used, or at perhaps 10, 20, 30, or 40 m
if the metric system is being employed. Cross-sectioning consists of observing
ground elevations and their corresponding distances left and right perpendicular
to the centerline. Readings must be taken at the centerline, at high and low
points, and at locations where slope changes occur to determine the ground profile
accurately. This can be done in the field using a level, level rod, and tape.
Plate B.5 in Appendix B illustrates a set of field notes for cross-sectioning.