How Brake Failure Works

By: Chris Marlowe  | 

Runaway Truck Ramps

Runaway truck ramps, also called truck escape ramps or TERs, can be found on highways that traverse steep downgrades. Contrary to what their name implies, TERs aren't just for folks driving big rigs. Drivers with overheated and malfunctioning breaks mainly find runaway truck ramps useful in two situations:

  • When braking problems arise in regions of heavy traffic and population on short, steep hills.
  • In sparsely inhabited mountain regions on long grades [source: Dragnet].

For more than 60 years, runaway truck ramps have been constructed in areas where frequent accidents involving big trucks have occurred. They may also be used as a preventative measure to keep children riding on school buses safe. Although they can be constructed anywhere, they are most often located in mountainous states.


When designing runaway truck ramps, engineers must consider the width of a vehicle as well as its weight and the approximate speed at which it might be traveling. One design is known as the gravel arrester bed. Studies have determined that these beds are more effective in slowing and stopping vehicles if rounded gravel from riverbeds is used, rather than crushed gravel. Another method used to construct TERS is to stretch a series of nets formed from aircraft cable across the ramp. The nets are fitted with energy absorbers that are mounted on both sides of the ramp's concrete walls. The use of these nets helps to stop vehicles and reduce the impact of the force created by slowing down or decelerating. One company has designed a ramp that can stop vehicles traveling as fast as 90 mph and weighing up to 90,000 pounds! [source: Transportation Research Boards]

When gearing down or using the parking brake doesn't work to stop your vehicle, you may be able to pull into one of these truck escape ramps. They're usually located to the right of the roadway.

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More Great Links


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