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What Is a Roundabout?

A modern roundabout is a circular intersection where drivers travel counterclockwise around a central island.  It is engineered to maximize safety and minimize traffic delay, and there are no traffic signals. The entering traffic yields to traffic already in the roundabout, which keeps traffic from locking up and creates efficient traffic flow.

How to Drive in a Roundabout

  1. Slow before entering.  This allows you to anticipate gaps in traffic, and lets drivers in the roundabout know you are preparing to yield.
  2. Yield to drivers circulating from the left.  Look left for vehicles before reaching the yield line.  If no vehicles are coming from the left and no pedestrians are in the crosswalk, there is no reason to stop.  
  3. Once you are in the roundabout, you have the right of way and entering traffic must yield to you.
  4. Stay to the right of the central island.  Traffic moves counterclockwise in a roundabout.
  5. Watch for bicycles and pedestrians when exiting the roundabout, and use your right turn signal to indicate you are exiting.

How to Drive in a Mini-Roundabout

  • Yield on entry and move in a counterclockwise direction, just like a full-size roundabout.
  • Use a turn signal before entering a mini-roundabout if turning left or right onto a side street. If continuing on the same street, no signal is needed. 
  • Signaling before entering improves efficiency because of the tighter constraints and shorter reaction times compared to a full-size roundabout.
  1.  Benefits
  2. Locations
  3. Mini vs. Full Roundabouts
Benefits of Roundabouts
Modern roundabouts have been shown to:
  • Keep traffic moving. Roundabouts reduce stopping, delays, and backups.
  • Reduce the number of accidents.  Studies also show that accidents at modern roundabouts are typically minor due to lower traffic speeds, and the possibility of dangerous t-bone and head-on collisions is virtually eliminated.
  • Reduce vehicle emissions due to decreased idling times.
  • Typically cost less to construct than signalized intersections, and eliminate the cost to power and maintain traffic signals.
  • Increase pedestrian safety. Pedestrians only cross one direction of traffic before reaching a median. 
  • Increase green space around and within the center island and along approaching streets. Roundabouts minimize the number of lanes needed to move the same amount of traffic compared to a traditional signalized street network.