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Neighborhood Traffic Management Program (NTMP)

Tools to Address Speeding and Traffic Volumes

Forced Turn Islands, Barriers, and Channelization

Top view of a street with forced turn islands

Make sure problems do not move elsewhere.

Temporary installation is highly recommended for initial evaluation.

These are traffic islands or curbs specifically designed to prevent traffic from making certain movements at an intersection or to force the traffic into specific patterns. They are sometimes referred to as "Pork Chops" or right-turn islands.

Care should be taken to evaluate the effects of diverted traffic on adjacent streets. Problems could be simply transferred from one location to another.

Access to residences may also be adversely affected so coordination with neighborhoods is important.

Temporary Island Installation

Forced turn temporary installation

Temporary Installation

Baldwin Park, CA

Force turn permanent installation

Permanent Installation

PROS

  • Potential to reduce traffic speed.
  • Reduces traffic volumes.
  • Can be used to reduce cut-through traffic.
  • Can be evaluated on temporary basis first.
  • Self-enforcing.
  • Landscaping possible.

CONS

  • May reduce access for emergency vehicles.
  • Diversion to longer routes may cause inconvenience to and be opposed by affected residents.
  • Care needed if placed on transit routes.
  • May transfer problems elsewhere.
  • Need to allow bicycle access.
Summary of Effectiveness
Volume Reduction No
Speed Reduction Likely
Safety Improvement Possible
Streets to Use On Collector, Local Local/Collector
Use on Bus Route Check Routes
Use with Curbs and Gutters Yes
Spot or Area-wide Use Spot
Emergency Service Access Issues Possible
Impacts on Arterials Possible
Change in % Truck Unknown
Environmental Changes Unknown
Dependence on enforcement No
Level of Violation Self-enforced
Aesthetics and Landscaping Possible