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Portland Bureau of Transportation

Phone: 503-823-5185

Fax: 503-823-7576

1120 SW Fifth Ave, Suite 800, Portland, OR 97204

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Semi-diverters are curb extensions or islands that block one lane of the street.


Semi-diverters prevent drivers from entering or exiting certain legs of an intersection. Strategically located, semi-diverters can effectively reduce traffic volumes on a street.


Semi-diverters are very effective in reducing volumes.
Semi-diverters cost approximately $5,000 - 20,000.
Parking Impacts:
Semi-diverters may affect curbside parking opportunities opposite the device to permit emergency vehicle access.
Transit Service Impacts:
Semi-diverters are typically only considered on non-transit streets.
Emergency Services Impacts:
Semi-diverters allow a higher degree of emergency vehicle access than cul-de-sacs or diagonal diverters. Semi-diverters can be designed to allow emergency vehicle access, but careful consideration needs to be given to their use on primary fire response routes.
Noise Impacts:
Other Considerations:
Semi-diverters apply to all drivers, including local residents. Very special care must be taken to consider the availability, capacity, and appropriateness of the alternative routes drivers might use if a semi-diverter is constructed.
Examples In Portland:
SW Virginia at Taylors Ferry
SE 39th at Clinton and Lincoln Streets    Picture
Boones Ferry Road at Terwilliger    Picture