Illustrative design aid, not a grading design. The sample data are a synthetic 300 m by 200 m surface, not a survey. Shrink and swell are your own inputs; the default values are illustrative and are not soil properties. Haul cost is not modelled.
Part 1. Grid method (DEM differencing against a design plane)
Part 2. Road: average end area
Section area at depth h is (width + side slope x h) x h, with level ground across the width. Cut and fill areas are averaged separately between stations.