Runaway truck ramp

A runaway truck ramp, runaway truck lane, escape lane, emergency escape ramp, or truck arrester bed is a traffic device that enables vehicles which are having braking problems to safely stop. It is typically a long, sand- or gravel-filled lane connected to a steep downhill grade section of a main road, and is designed to accommodate large trucks or buses. It allows a moving vehicle's kinetic energy to be dissipated gradually in a controlled and relatively harmless way, helping the operator stop it safely.

Design

Emergency escape ramps are usually located in mountainous areas which cause high construction costs and present difficult site selection. A ramp may cost US$1 million. Designs include:

*''Arrester bed'': a gravel-filled ramp adjacent to the road that uses rolling resistance to stop the vehicle. The required length of the bed depends on the mass and speed of the vehicle, the grade of the arrester bed, and the rolling resistance provided by the gravel.
*''Gravity escape ramp'': a long, upwardly inclined path parallel to the road. Substantial length is required. Control can be difficult for the driver; problems include rollback after the vehicle stops.
*''Sand pile escape ramp'': a short length of loosely piled sand. Problems include sudden, forceful deceleration; sand being affected by weather conditions (moisture and freezing); and vehicles vaulting and/or overturning after contacting the sand pile.
*''Mechanical-arrestor escape ramp'': a proprietary system of stainless-steel nets transversely spanning a paved ramp to engage and retard a runaway vehicle. Ramps of this type are typically shorter than gravity ramps, and can work even on a downhill grade. These systems tend to be costly, but may save expensive real estate in crowded areas, and prevent even more costly crashes. One such ramp at Avon, Connecticut in the United States has an electrically heated pavement surface to prevent snow and ice accumulation.
*''Alternatives'': such as a vehicle arresting barrier.

Location

Emergency escape ramps are usually located on steep, sustained grades, as in mountainous areas. Long descending grades can allow high vehicle speeds to be reached, and truck brakes can overheat and fail through extensive use. The ramps are often built before a critical change in the radius of curvature of the road, or before a place that may require the vehicle to stop, such as before an intersection in a populated area.
The placement criteria can vary from one region/country to another.

Gallery

File:Runaway truck ramp east of Asheville, NC IMG 5217.JPG, Runaway ramp on Interstate 40 east of Asheville, North Carolina
File:Great Eastern Highway Truck Arrester Bed.JPG, An arrester bed on Great Eastern Highway in Western Australia, located at the bottom of a hill before an intersection
File:Escape Ramp In China Expwy G4511-cropped.jpg, An emergency escape ramp on the G4511 in Heyuan, China
File:TER US 44 Westbound Avon, CT, USA.png, Mechanical-arrestor truck escape ramp (with heated pavement) on US 44 westbound in Avon, Connecticut
File:20141118 Misiryeong Penetrating Road (Emergency Escape Ramp)2.jpg, An emergency escape ramp on Misiryeong Penetrating Road in Gangwon Province, Korea
File:I-176Runway.jpg, I-176 runaway truck ramp in Morgantown, PA
File:Escape ramp on the A7 near Amskroud, Morocco.jpg, A 100 meter long gravel escape ramp downhill on the A7 near Amskroud in Morocco.
File:Thailand's escape ramp.jpg, An emergency escape ramp on the AH1 in Tak, Thailand
File:Traverse City Runaway Truck Ramp.png, M-72 runaway truck ramp in Traverse City, Michigan
File:Emergency stopping lane in Muğla, Turkey.jpg, Emergency stopping lane in Muğla, Turkey
File:Runaway truck ramp near Silverthorne, Colorado.png, Runaway truck ramp on Interstate 70 near Silverthorne, Colorado.
File:Emergency exit on the I-5 road between Ruse and Byala.jpg, Improvised emergency exit for runaway vehicles on the I-5 near Byala, Bulgaria

See also

* Catch points
* Derail
* Engineered materials arrestor system
* Runway safety area (RSA/RESA) for airplanes

References

External links

Design considerations

Query executed on live Openstreetmap data. Move the map to your area of interest and press RunVideo: runaway truck on gravel ramp

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Road safety
Trucks
Road infrastructure