Speed Humps:

Speed humps are paved (usually asphalt) and approximately 75 to 100 mm (3 to 4 in) high at their center, and extend the full width of the street with height tapering near the drain gutter to allow unimpeded bicycle travel. Speed humps should not be confused with the speed “bump” that is often found in mall parking lots. There are several designs for speed humps. The traditional 3.7-m (12-ft) hump has a design speed of 24 to 32 km/h (15 to 20 mi/h), a 4.3-m (14-ft) hump a few miles per hour higher, and a 6.7-m (22-ft) table has a design speed of 40 to 48 km/h (25 to 30 mi/h). The longer humps are much gentler for larger vehicles.



  Purpose
• Reduce vehicle speeds. Raised measures tend to have the most predictable speed reduction impacts.
• Enhance the pedestrian environment at pedestrian crossings.
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  Considerations
• Do not use if on a sharp curve.
• If the street is a bus route or primary emergency route, the design must be coordinated with operators. Usually, some devices are acceptable if used prudently — one device may be appropriate and may serve the primary need (e.g., if there is a particular location along a street that is most in need of slowing traffic and improving pedestrian conditions).
• The aesthetics of speed humps and speed tables can be improved through the use of color and specialized paving materials.
• Noise may increase, particularly if trucks use the route regularly.
• May create drainage problems on some streets.
• Speed humps and tables should be properly designed and constructed to reduce the chance of back problems or other physical discomfort experienced by vehicle occupants. Tight tolerances are required during construction.
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  Estimated Cost
The cost for each speed hump is approximately $1,000. Speed tables are $2,000 to $15,000, depending on drainage conditions and materials used.
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  Case Studies
Berkeley, CA 
Clark County, WA 
Tucson, AZ 
Portland, OR 
Portland, OR 
Sarasota, FL 
Clark County, WA 
Tucson, AZ 
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U.S. Department of Transportation Federal Highway Administration