Pedestrian Safety Guide and Countermeasure Selection System

 

A speed hump. Source: Gina Coffman (2012)


 

 

 

Speed Humps

Speed humps are paved (usually asphalt) and approximately 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 12-ft hump has a design speed of 15 to 20 mi/h, 14-ft hump a few mph higher, and a 22-ft table has a design speed of 25 to 30 mi/h. The longer humps are much gentler for larger vehicles.

Speed humps can also be designed with two, 1-ft slots to allow for vehicles with wide wheelbases such as buses and emergency vehicles to pass through them without having to go over the measure. These are typically called speed cushions.

Purpose

Speed humps are vertical traffic control measures that tend to have the most predictable speed reduction impacts. They can also be used to enhance the pedestrian environment at pedestrian crossings.

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.

Estimated Cost

Approximately $1,500 to $5,500, depending on the height, width of the road, drainage conditions, and design. The service life is 20 years for asphalt, and 40 years for concrete.

Case Studies

Berkeley, CA
Clark County, WA
Portland, OR
Albemarle, Virginia
New York City, New York