- Speed cushion
Speed cushions are
traffic calmingdevices designed as several small speed humpsinstalled across the width of the road with spaces between them. They are generally installed in a series across a roadway resembling a split speed hump. The design of speed cushions forces cars to slow down as they ride with one or both wheels on the humps. However, the wider axle of emergency vehicles such as fire engines and ambulances allows them to straddle the cushions without slowing down or increasing response times.Although the newest available traffic calmingdevice, speed cushions are rapidly growing in popularity due to their ability to slow cars without affecting emergency vehicles.
Typical speeds resulting from speed cushions are 15-25 miles per hour.
Speed cushions have several distinct advantages over similar
traffic calmingdevices. Many municipalitiesare challenged by opposition to speed humpsand speed tablessince they slow down emergency vehicles. Speed cushions address this problem by allowing larger vehicles to straddle the cushion without slowing down. This is also an advantage for buses, as lower floor vehicles can sometimes ground out on traditional humps.
Speed cushions are also often less costly than
speed humpsor tables while most cities report them to be just as effective.
Speed cushions can be constructed of
asphalt, concrete, or rubber. Several trade-offs must be made when selecting the material for a new speed cushion. It is easier and more temporary to apply preformed rubber devices; prefabricatedrubber cushions must simply be assembled and bolted down to meet standard specifications. For more permanence and greater effect in slowing traffic, asphalt or concrete construction is preferred due to the material's rigidity and durability. Constructing small cushions uniformly by pouring asphalt or concrete requires some skill and practice. Uniformity of design is desirable to ensure that motorists develop consistent expectations regarding speed and impact of similar devices.
Speed humpsare similar to speed cushions although they are solid units spanning the width of the road. Speed tablesare longer than speed humps with a flat section in the middle. Cars are slowed to higher speeds than with speed humps. Speed bumpsare significantly smaller than speed humps and used in areas where speed must be slowed nearly to a halt.
* [http://www.ci.austin.tx.us/roadworks/cushions.htm City of Austin Speed Cushion Description]
* [http://www.trafficlogix.com/speed-cushions.asp Traffic Logix Speed Cushion Description]
* [http://www.dft.gov.uk/pgr/roads/tpm/tal/trafficmanagement/speedcushions?page=2 UK Department for Transport Speed Cushion Description]
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