What purpose do escape ramps serve on steep mountain grades?

Escape ramps on steep mountain grades are specifically designed to stop runaway vehicles safely. When vehicles experience brake failure or other issues while descending steep grades, the ramps provide a safe area for those vehicles to reduce speed and come to a complete stop without posing a danger to other motorists. These ramps are constructed with materials that can help to slow down the vehicles, such as gravel or sand, and have a gentle incline to assist in bringing the vehicle to a halt.

While rest areas and scenic overlooks serve different purposes, they do not address the critical need for safety in the context of runaway vehicles. Emergency vehicle passage, although important, is not the primary function of escape ramps. Thus, the correct answer highlights the essential safety role these ramps play in protecting both runaway vehicles and other road users in the challenging driving conditions presented by steep mountain grades.