Tag:highway=escape
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 highway = escape
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| Description |
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Emergency lane beside long descending slopes for trucks to stop after brake failure. 
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| Group: highways |
| Used on these elements |
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| Useful combination |
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Status: approved
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A 
runaway truck ramp, runaway truck lane, emergency escape ramp or truck arrester bed is a traffic device that enables vehicles that are having braking problems to safely stop. It is typically a long, sand or gravel-filled lane adjacent to a road with a steep grade, and is designed to accommodate large trucks. The deep gravel allows the truck's momentum to be dissipated in a controlled and relatively harmless way, allowing the operator to stop it safely.
Examples
Most motorways have them in case of steep and/or long downhill sections.
Type of escape lane overview
- 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. A large 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 large 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 that engage and retard a runaway vehicle. Ramps of this type are typically shorter than gravity ramps and can have a downhill grade. One such ramp in Avon, CT, USA has an electrically-heated pavement surface to prevent snow and ice accumulation.
- Alternatives
- Such as a vehicle arresting barrier.
Tagging
- Use highway=escape for the escape lane itself
- escape:type=* to tag different types of escape lane. (see on taginfo a list of currently used values)
- Before the escape itself, add access:lanes=* with yes|yes|escape in the case of 3 lanes, of which the right lane leads to the escape.
See also
- Runaway truck ramp on Wikipedia
- Signs for this feature in Wikimedia Commons
- Proposed features/escape lane
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