Device name(s): Center Island Narrowing/Pedestrian Refuges/Slow Points

Medians or Center Island Narrowing

Approximate Cost:$5000 – $7000

Definition: Center islands are raised medians placed between two directions of traffic, often within a center turn lane.  Center islands are installed to narrow the width of the road which can reduce motorists’ speeds as they travel through the area.  Center islands are useful in reducing potential conflicting turning movements. The purpose of medians is to: narrow the roadways, channelized the regular traffic, passively control turning movement, provide pedestrian mid-road safe refuge, and create landscape/streetscape enhancement. Slow points are small islands placed their intersections or mid-block with the intent of slowing vehicles and of improving pedestrian safety. Islands without any vertical deflection result in an average speed reduction of 7%, or from an average of 34.9 to 32.3 mi./h.

Fast Facts:

  • Can be used on Local Street- yes
  • Can be used on Collector- yes
  • Can be used on Arterial- yes
  • Reduces Speed- yes
  • Reduces Volume- no
  • Noise Impact- no
  • Restricts Access- possible
  • Bicyclist Impact-  no
  • Transit Impact- no
  • Parking Impact- possible
  • Emergency Response Impact- no


  • eliminates turning or passing conflicts
  • narrows road
  • provide buffer between opposing traffic
  • allows pedestrians to cross half of the street at a time (pedestrian refuge)
  • makes pedestrian crossing points more visible to drivers
  • channelizes traffic and inhibit prohibited turning movement
  • prevent vehicles from passing turning vehicles
  • may result in geometric improvement
  • improves streetscape through landscaping
  • slower traffic
  • increases pedestrian safety
  • can have positive aesthetic value
  • reduce traffic volume
  • people with mobility impairments benefit from divided and decreased crossing distances due to the presence of the pedestrian refuge in the center of the street


  • increases regular maintenance
  • may require loss of parking spaces
  • some inconveniences to residents by raised median in reaching their driveways
  • may result in additional congestion as cars cannot pass stopped, left turning vehicles
  • reduces the space for motor vehicles to pass bicycles
  • the reduction effort is somewhat limited because vehicles do not have to alter their path


  • adequate pavement width
  • entrances to residential areas
  • wide street where pedestrians need to cross
  • curves
  • 85th percentile speed is 5 mph above the speed limit or greater
  • 60% of households in affected area must support