For trucks that don't do that or that suffered a brake failure for other reasons, there are escape ramps filled with sand or other material to reduce the speed of runaway trucks. (mechanics.stackexchange.com)
When you see the area on the side of the road for runaway trucks they are there because when you use your brakes for a long period of time going down a mountain side the brakes will stop working when they can no long absorb heat. (larrymillertoyota.com)
-- Truckers that use improper breaking techniques can cause brake failures that lead to runaway trucks which often occur at intersections, tollbooths, off - ramps and railroad crossings. (phoenixcriminaldefense.com)