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Neighborhood Traffic Management Program (NTMP)

Tools to Address Speeding and Traffic Volumes

Half Closures and Semi-Diverters

Top view of a street with semi-diverter

Semi-diverters are extensions from the curb or islands - usually extending from a corner of an intersection that block one directional lane of the street.

They are used to prevent drivers from making certain turn movements at an intersection. Semi-diverters can effectively reduce traffic volumes on a street although the diverted traffic may impact adjacent streets. Semi-diverters are very effective in reducing volumes at specific locations.

Semi-diverters affect all drivers, including local residents. Thus, care must be taken to consider the impacts on alternative routes as well as neighborhood access routes.

N/A

Temporary Installation

Culver City, CA

Semi-diverter permanent installation

Permanent Installation

PROS

  • Reduces traffic volume.
  • Maintains access for residents.
  • Reduces cut-through traffic.
  • Reduces crossing distance for pedestrians.
  • Landscaping possible.
  • OK for emergency vehicles.
  • Can provide 2-way access for bicycles.

CONS

  • May divert traffic to parallel streets.
  • May increase trip length for some residents.
  • 1-2 curbside parking spaces lost.
  • Maintenance needs if landscaped.
Summary of Effectiveness
Volume Reduction Yes
Speed Reduction Yes
Safety Improvement Unknown
Streets to Use On Collector, Local Local/Collector
Use on Bus Route Possible
Use with Curbs and Gutters Yes
Spot or Area-wide Use Spot
Emergency Service Access Issues Yes
Impacts on Arterials Possible
Change in % Truck Unknown
Environmental Changes Unknown
Dependence on enforcement Some
Level of Violation N/A
Aesthetics and Landscaping Possible