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Neighborhood Traffic Management Program (NTMP)

Tools to Address Speeding and Pedestrian Safety

Center Island Narrowing

Street top view with a center island narrowing

Often used with a marked crosswalk

Raised islands are installed along the center of the street to effectively narrow the travel lanes in each direction. They can be landscaped to improve the aesthetics of the location and can have a built in pedestrian refuge when placed in conjunction with a mid-block crosswalk.

Parking may need to be removed along the affected roadway section. Bicycle users may feel more vulnerable on narrower lanes.

They may also be called mid-block medians, median slow points, or median chokers.

San Marino, CA

Center island narrowing temporary installation

Temporary Installation

Baldwin Park, CA

Center island narrowing permanent installation

Permanent Installation

PROS

  • Results in reduction in speeds.
  • Enhances pedestrian environment.
  • Helps safety when used on curved roads by reducing speed.
  • Can be evaluated on temporary basis first.
  • Can be landscaped.
  • Can be a "Gateway" feature.

CONS

  • May result in loss of on-street parking.
  • Moderately expensive measure if landscaped.
  • Center islands may be hit at night unless well marked.
  • Reduced lane widths not favored by bicycle users.
Summary of Effectiveness
Volume Reduction No
Speed Reduction Yes (Slight)
Safety Improvement Unknown
Streets to Use On Collector, Local Local/Collector
Use on Bus Route Yes
Use with Curbs and Gutters Yes
Spot or Area-wide Use Spot
Emergency Service Access Issues No
Impacts on Arterials No
Change in % Truck Unknown
Environmental Changes No
Dependence on enforcement No
Level of Violation N/A
Aesthetics and Landscaping Limited