It is very difficult to evaluate the comparative overall costs of flat vs. steep side slopes. The advantages of steep slopes are the smaller volume of earthwork required and the smaller amount of right of way involved. In large cuts or fills it may be more economical to bench than to flatten slopes. On the other hand, the cost involved in stabilizing, planting, and perpetual maintenance may sometimes exceed the cost of grading and right of way required to provide a flatter slope. This illustrates that the steepest slopes permissible are not always the most economical.
Sometimes the most economical solution is to use a retaining wall. A short length of low retaining wall, at a critical section, may eliminate the need for expensive right-of-way, avoid damage to existing improvements, and considerably reduce the volume of earthwork required.
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