Speed cushion

Speed cushions are traffic calming devices designed as several small speed humps installed 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 calming device, speed cushions are rapidly growing in popularity due to their ability to slow cars without affecting emergency vehicles.

Results

Typical speeds resulting from speed cushions are 15-25 miles per hour.

Advantages

Speed cushions have several distinct advantages over similar traffic calming devices. Many municipalities are challenged by opposition to speed humps and speed tables since 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 humps or tables while most cities report them to be just as effective.

Composition

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; prefabricated rubber 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.

imilar measures

Speed humps are similar to speed cushions although they are solid units spanning the width of the road.

Speed tables are longer than speed humps with a flat section in the middle. Cars are slowed to higher speeds than with speed humps.

Speed bumps are significantly smaller than speed humps and used in areas where speed must be slowed nearly to a halt.

References

* [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]