Independent roadway grade lines that fit the terrain with a minimum of cuts and fills reduce exposed areas subject to erosion. Alignment and grade, consistent with highway safety criteria, must be blended or fit to the natural landscape to minimize cut and fill sections and reduce erosion and costly maintenance. Slopes of the roadway cross section should consider soil stability, climatic exposure, geology, proposed landscape treatment, and maintenance procedures.

Depressed roadways and underpasses require careful consideration of drainage to avoid deposition of sediment and debris on the highway and in drainage facilities. Both ground and surface water can do the following:

The cross section can be varied, if necessary, to minimize erosion and to facilitate safety and drainage. Generally, good landscaping and drainage design are compatible with both erosion control and safety to vehicles. Right-of-way constraints often prohibit extreme flattening of embankment slopes, but they should be an important consideration to the designer in their effect on erosion.