Speed bumps are asphalt mounds constructed on streets and spaced 300 to 600 feet apart. Portland uses two different shapes of speed bump according to the conditions and needs of a given street. On residential streets where speeds of 25 mph are desired, speed bumps that are 14 feet wide and ramp up to a height of 3 inches might be used. On streets where speeds of 30 mph are desired, 22 foot speed bumps might be used. On streets used by transit vehicles, are considered primary fire response routes by the Portland Fire Bureau or have exceptionally high volumes, the 22 foot bump may be selected instead of the 14 foot speed bumps. Portland has also investigated the Offset, or Split, speed bump. A 22-foot bump is split in half down the centerline of the street. Each half is offset from the other and a small splitter island is constructed. Offsetting the two bump halves permits emergency vehicles to drive around the bump portions, significantly reducing delay.
14 Foot Speed Bumps Click here for photo
22 Foot Speed Bump Click here for photo
Split Speed Bump Click here for photo
Speed bumps are intended to reduce vehicle speeds.
Fourteen-foot speed bumps are very effective at encouraging 25 mph vehicle speeds. Twenty-two-foot speed bumps are very effective at encouraging 30 mph vehicle speeds.
Effectively reduce vehicle speeds
Do not require parking removal
Pose no restrictions for bicycles
Do not affect intersection operations
Can possibly increase traffic noise from braking and acceleration of vehicles, particularly buses and trucks
Slows fire vehicles
Asphalt speed bumps cost approximately $1,000 - 1,500 each. The islands for the Split speed bumps adds $5000 to each location. Please contact Recycled Technology for current pricing on Rubber speed bumps.
Transit Service Impacts:
Like other vehicles, buses must cross a speed bump at reduced speeds. Experience shows that 22 foot speed bumps do not impede transit service or scheduling. Riding over speeds bumps does not significantly bother transit riders.
Emergency Services Impacts:
Like other vehicles, emergency response vehicles must cross a speed bump at reduced speeds. The speed bump design selected for any street takes into consideration whether it is used as a primary response route. The Portland Fire Bureau reviews all speed bumps proposed on primary response routes.
Speed bumps may generate some noise from drivers accelerating or from objects not secured inside the vehicles.
Traffic volumes typically decrease slightly after speed bumps are constructed. Traffic on neighboring streets must monitored for diversion.
Speed bumps are not constructed on grades greater than 8%.
Examples In Portland:
SW Boones Ferry Rd - Taylors Ferry to Terwilliger; SE Harold - 52nd to Foster Rd; SW 15th - Broadway to Prescott; SW Troy - Capitol Hwy to Capitol Hill Rd; SE 115th - Harold to Holgate; NE 87th - Killingsworth to Prescott; NE Fargo - 102nd to 122nd