Center-Island Narrowings

A center island narrowing is a raised island located along the centerline of a street that narrow the travel lanes at that location. Center island narrowings are often landscaped to provide a visual amenity. Placed at the entrance to a neighborhood, and often combined with textured pavement, they are often called “gateway islands.” Fitted with a gap to allow pedestrians to walks through at a crosswalk, they are often called “pedestrian refuges.”

Center Island Narrowings are good for entrances to residential areas, and wide streets where pedestrians need to cross.

Advantages:

  • Center Island Narrowings increase pedestrian safety
  • If designed well, they can have positive aesthetic value
  • They reduce traffic volumes

Disadvantages:

  • Their speed-reduction effect is somewhat limited by the absence of any vertical or horizontal deflection
  • They may require elimination of some on-street parking

Effectiveness:

  • Average of 7% decrease in the 85th percentile travel speeds, or from an average of 34.9 to 32.3 miles per hour (combined average for various narrowing measures, taken from a sample of 7 sites)

Similar Measures:

  • If a roadway is narrowed out from the curbs at an intersection, you have a Neckdown

Cost Estimate(s):

  • $8,000 – 15,000 (Portland, OR), $5,000 (Sarasota, FL)
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