Road section. Cut and fill slopes in earth shall be not less than
one on two. Subbase, at least 30 feet in width, shall consist of a
bottom course of at least eight inches of run of bank gravel, shale
or slag and a top course of at least four inches of well graded run
of bank gravel or washed gravel with no particles of material larger
than two inches in diameter. The subbase shall be crowned, shaped
to a smooth grade and well compacted, and all underground utilities
and drainage structures shall be completed before the surfacing is
applied. Clay content shall be 2% maximum.