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Neighborhood Traffic Management Program (NTMP)

Tools to Address Speeding and Traffic Volumes

Chicanes

Street top view with chicanes

Chicanes can result in reduced speeds due to curved travel paths

Chicanes are curb extensions or islands that alternate from one side of the street to the other, forming S-shaped curves.

They are appropriate for mid-block locations only. Most effective with equivalent volumes on both approaches. Typically consist of a series of at least three curb extensions. Can use on-street parking to create chicane. European manuals recommend shifts in alignment of at least one lane width, deflection angles of at least 45 degrees, and center islands to prevent drivers from taking a straight "racing line" through the feature.

Chicanes may also be called deviations, serpentines, reversing curves, twists, and staggerings.

-The Institute of Transportation Engineers (ITE)

Temporary Chicane

Chicanes temporary installation

Temporary Installation

Seattle, WA

Chicanes permanent installation

Permanent Installation

PROS

  • Volume and speed reduction possible.
  • Self-enforcing.
  • Provides opportunity for roadway beautification.
  • Can be landscaped.
  • Can be a "Gateway" feature.

CONS

  • Must be designed to avoid drivers encroaching over center line.
  • Can affect street sweeping.
  • Parking can be affected.
  • Driveway access can be affected.
  • Potential Pedestrian/Bike/Car conflicts.
  • Potential for head-on collision.
Summary of Effectiveness
Volume Reduction Yes
Speed Reduction Yes
Safety Improvement Yes
Streets to Use On Collector, Local Local
Use on Bus Route With Care
Use with Curbs and Gutters Yes
Spot or Area-wide Use Both
Emergency Service Access Issues Minimal
Impacts on Arterials Possible
Change in % Truck Unknown
Environmental Changes Unknown
Dependence on enforcement No
Level of Violation N/A
Aesthetics and Landscaping Possible