Traffic Calming
28. Speed Hump / Table

Speed humps are paved (usually asphalt) and approximately 3-4 inches high at their center, and extend the full width of the street. Speed humps should not be confused with a speed "bump" that is often found in mall parking lots. There are several designs for speed humps. The traditional 12-foot hump has a design speed of 15 to 20 mph, a 14-foot one a few mph higher, and a 22-foot table, of 25 to 30 mph. The longer humps are much gentler for larger vehicles.

A speed table is a term used to describe a very long and broad speed hump, or for a flat-topped speed hump, where sometimes a pedestrian crossing is provided in the flat portion of the speed table. The speed table can either be parabolic, making it more like a speed hump, or trapezoidal, which is used more frequently in Europe. Speed tables can be used in combination with curb extensions where parking exists.

Purpose:
  • Reduces vehicle speeds. Raised measures tend to have the most predictable speed reduction impacts.
  • Enhances the pedestrian environment and pedestrian crossings.

Considerations:

  • Do not use if sight distance is limited and/or if the street is on a steep grade.
  • If the street is a bus route or primary emergency route, 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.

Estimated cost

The cost for each speed hump is approximately $2,000. Speed tables are $5,000$15,000, again depending on drainage conditions and materials used.