Speed Cushions/Speed Lumps/Flat-Top Speed Cushions

Device name(s): Speed Cushions/Speed Lumps/Flat-Top Speed Cushions

Speed Cushions or Speed Lumps2 Speed Cushions or Speed Lumps

Approximate Cost: $2,500-$6,000

Speed Reduction: 5 mph

Definition: Speed lumps are similar to speed humps in that they are rounded, tapered raised areas placed across a roadway to reduce speeds. However, speed lumps are designed to allow emergency vehicles to travel along a roadway with  minimal  impact  to  response   times. S peed lumps are supplemented with appropriate striping  and signage  to adequately inform motorists of the traffic calming device. Usually 22 feet long and 3.5 inches high. Speed cushions are most effective if used in a series; spaced 300 to 500 feet apart. Similar to speed humps but they are divided into sections so wide wheelbase vehicles can straddle them. As such, they cab more easily accommodate transit, fire engines, and other emergency response vehicles.

Fast Facts:

  • Can be used on Local Street- Yes
  • Can be used on Collector- Possible
  • Can be used on Arterial- No
  • Reduces Speed- Yes
  • Reduces Volume- Possible
  • Noise Impact- Yes
  • Restricts Access- No
  • Bicyclist Impact- No
  • Transit Impact- No
  • Parking Impact- No
  • Emergency Response Impact- No

Advantages:

  • Effective in reducing speeds
  • Minimal impact to emergency response times
  • Reduces speeds, 3-7 mph
  • Increases pedestrian safety
  • Self-enforcing
  • Relatively inexpensive
  • Does not delay emergency vehicles
  • Parking may be allowed on cushion
  • can reduce volume

Disadvantages:

  • Increases regular maintenance
  • May generate minor noise at cushion when traversed by large trucks and buses
  • Some discomfort for short wheel-based vehicles
  • may divert traffic to parallel streets that do not have traffic calming devices
  • may increase emergency response times
  • not aesthetically pleasing

Criteria/Application(s):

  • 85th percentile speed is 32mph or greater
  • 70% of households in affected area must support
  • Spacing of 300-500 feet

Speed Cushion or Speed Lumps

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