Description:

• rounded raised areas of pavement typically 12 to 14 feet in length
• often placed in a series (typically spaced 300 to 600 feet apart)
• sometimes called road humps or undulations

Applications:

• residential streets
• not typically used on major roads, bus routes, or primary emergency response routes
• midblock placement, not at an intersection
• not on grades greater than 8 percent
• work well with curb extensions

Design/Installation Issues: typically 12 to 14 feet in length; other lengths (10, 22, and 30 feet) reported in practice in U.S. speed hump shapes include parabolic, circular, and sinusoidal hump heights range between 3 and 4 inches with trend toward 3 - 3 ½ inches maximum difficult to construct precisely; may need to specify a construction tolerance (e.g. ± 1/8 inch) on height often have signage (advance warning sign before first hump in series and warning sign or object marker at hump) typically have pavement marking (zigzag, shark's tooth, chevron, zebra) taper edge near curb to allow gap for drainage some have speed advisories bicyclists prefer that it not cover or cross a bike lane

Potential Impacts:

• no effect on non-emergency access
• speeds determined by height and spacing; speeds between humps have been observed to be reduced between 20 and 25 percent on average
• based on a limited sample of sites, typical crossing speeds (85th percentile) of 19 mph have been measured for 3½ inch high, 12 foot humps and of 21 mph for 3 inch high, 14 foot humps; speeds have been observed to rise to 27 mph within 200 feet downstream
• speeds typically increase approximately 0.5 mph midway between humps for each 100 feet of separation
• studies indicate that traffic volumes have been reduced on average by 18 percent depending on alternative routes available
• studies indicate that collisions have been reduced on average by 13 percent on treated streets (not adjusted for traffic diversion)
• most communities limit height to 3-3½ inches, partly because of harsh ride over 4-inch high humps
• possible increase in traffic noise from braking and acceleration of vehicles, particularly buses and trucks

Emergency Response Issues:

• Concern over jarring of emergency rescue vehicles
• Approximate delay of between 3 and 5 seconds per hump for fire trucks and up to 10 seconds for ambulance with patient

Typical Cost:

• Approximately $2,000 (1997 dollars)

For additional detail, refer to ITE’s Recommended Practice entitled Guidelines for the Design and Application of Speed Humps.  Visit the ITE Bookstore for more information about this publication.

1627 I ("Eye") Street, NW, Suite 600
Washington, DC
20006-3538 USA
Phone: 202-785-0060
Fax: 202-785-0609
Send comments to:
ite_staff@ite.org

SPEED HUMP | SPEED TABLE | RAISED INTERSECTION | CLOSURE | NEIGHBORHOOD TRAFFIC CIRCLE | CHICANE | CHOKER | CENTER ISLAND NARROWING