A speed table is a traffic calming device designed as a long speed hump with a flat section in the middle. Speed tables are generally long enough for the entire wheelbase of a passenger car to rest on top.[1] The long, flat design allows cars to pass without slowing as significantly as with speed humps or cushions.[2] Because they slow cars less than similar devices, speed tables are often used on roads with typical residential speed limits.
Speed tables can also be signed as pedestrian crossings.
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Typical speeds resulting from 22 foot speed tables are 20-30 miles per hour. One sample of 8 sites found a 45% decrease in accidents per year with the use of speed tables.[3]
Speed tables are effective in calming traffic on streets where the speed limit needs to be maintained rather than slowing cars more significantly. Traffic speed, volumes, and accidents have been shown to decrease with the use of tables. Although not as responsive to emergency vehicles as speed cushions, speed tables cause less of a delay than humps and are typically preferred by fire departments over speed humps.[4]
Speed tables can be constructed of asphalt, concrete, or rubber. While traditionally most humps were constructed of asphalt or concrete, rubber is becoming increasingly popular due to several factors. Asphalt and concrete can be difficult to construct precisely while rubber products are pre-shaped to standardized sizes and thus consistently meet industry standards. An additional advantage is ease of installation, which is particularly beneficial when a city wants to test streets before deciding where to keep the devices. The simple installation process also allows for removal during the winter when snow is a concern (preventing damage to the humps by snow plows). In addition, unlike concrete and asphalt, which necessitate frequent and high cost replacement, rubber products are longer lasting and thus more cost-efficient.
Speed humps are similar to speed tables although they shorter in length with rounded tops. Humps slow cars more significantly than speed tables.
Speed cushions are a series of three humps that are ideal for use on streets when emergency vehicle response time is of primary concern
Speed bumps are significantly smaller than speed humps and are used in areas where speed must be slowed nearly to a halt.
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