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Where to Use Roundabouts

Appropriate conditions for roundabout installation:

  • Locations with high delays
  • Locations where traffic signals are not warranted
  • Four-way stop intersections
  • Intersections with more than four legs
  • Intersections with high left-turn flows
  • Intersections with unusual geometry
  • Intersections with changing traffic patterns
  • Locations where storage capacities for signalized intersections are restricted
  • Intersections that are important from an urban design or visual point of view


The following conditions require special design attention and hiring an experienced designer:

  • Locations where there is insufficient space for an acceptable outside diameter.
  • Locations where it would be difficult to provide flat (2% or less) entries into the roundabout.
  • Maximum grade greater than 4% around the circle,
  • A high number of pedestrians, a high percentage of large trucks, intersection junction at the top or bottom of a grade, and the close proximity of adjacent signals..

The design topics can be used as a checklist when designing roundabouts.

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