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Speed Bumps, Humps, and Cushions
Speed bumps, speed humps, and speed cushions (or "pillows") are vertical-deflection traffic
calming devices which were developed in the order listed and generally applied to low-volume residential streets. All three devices can be constructed from asphalt (most common), concrete, or rubber. Rubber devices are generally temporary, applied as an emergency intervention, or on a trial basis prior to installing permanent devices.
Speed bumps, which date from the early 1900's, are 3-4 inches tall and 12 inches in travel length. They have a design speed of 5 mph. They have been in common use for decades in the U.S., Europe, Australia, and other countries. While highly effective at slowing traffic, they introduce new problems: vehicle damage to large or low-carriage vehicles, spinal pain to the elderly or people with back pain, and engine/tire noise. Emergency responders complain that
firetrucks and ambulances must come to a dead stop before driving over them, slowing response times. Speed bumps are also dangerous for bicyclists. Early in their history, U.S. courts found speed bumps to be "patently unsafe".[2] Their use grew, nonetheless.
Speed humps were introduced in recent decades as a more gentle version of the speed bump. Like speed bumps, speed humps span an entire lane or street width, but measure 3-4 feet in length, and have a curved profile as high as one foot. Speed cushions are similar to speed humps in profile, but have a break which lines up with the wheelbase of utility vehicles such as refuse trucks, firetrucks, ambulances, and moving vans. This configuration allows large vehicles - and bicycles - to avoid the raised pavement entirely.
Another variation on speed bumps, humps, and pillows is the
speed table
, which is up to 12 feet in length and includes a flat middle portion. A speed table that covers an entire intersection is known as an intersection table or
raised intersection
.
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ALSO ON THE LIVABLE STREETS NETWORK
REFERENCES
Each source is referred to by the same number every time it is cited. Please keep citation style consistent.
[1] "Slowing Down Traffic: Traffic Calming Information." New York City Department of Transportation.
[2] Ewing, Reid H., 1998. Legal aspects of traffic calming, Institute of Transportation Engineers, Annual Meeting Compendium, 1998. Washington DC. http://www.ite.org/traffic/documents/AHA98B26.pdf
[3]
[4]
PICTURE REFERENCES
Pictures are cited in the order they appear above. Please keep citation style consistent.
[1] Pedestrian Bicycle Information Center Image Library, courtesy of Dan Burden.
[2]
