Escape ramps, used to stop trucks that have had brake failures on long downhill grades, are usually constructed in terrain where an ascending grade can be utilized to assist in stopping the vehicles. An arrester bed of noncompacting gravel is typically used to assist in stopping the truck and to prevent roll-back of trucks after having stopped. In terrain where an ascending grade is not available and the length available for ramp construction is limited, other energy absorbing means are needed. Some use has been made of gravel mounds at the end of escape ramps as an emergency measure to stop vehicles not stopped by the arrester bed. Documentation of the reaction of trucks striking these gravel mounds is very limited. The purpose of this study was to evaluate the reaction of trucks impacting transverse gravel mounds.
Mounds 1 foot, 2 feet, and 2.5 feet were tested singly and in groups of three. The test vehicles were two-axle dump trucks loaded with gravel. Test speeds were generally at 25 mph and 40 mph. The higher mounds were effective in slowing the truck without driver injury but truck damage in the form of bent tie rods was common and the front axles were bent on several trucks.
Most escape ramps are designed to use gravity as the primary deceleration mechanism. These ramps provide an exit from the roadway to an adjacent hills...
The objectives of this study are to: (1) review current truck escape ramp literature; (2) document all acceptable designs; (3) determine any and all s...
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