Modern roundabouts are among the new forms of intersection control in the United States. South Dakota does not currently have any roundabouts installed on the state highway or Interstate system, but three are currently programmed in the STIP. Two are planned in Sisseton and one in Watertown.

Roundabouts have been proven to provide a safe and efficient traffic flow. A number of safety studies have been researched by FHWA, the Insurance Institute for Highway Safety and numerous other state and private agencies.

Roundabouts move traffic safely through an intersection because of:

  • Slower speeds
  • Fewer conflict points
  • Reduction of T-bone (right-angle) and head-on collisions
  • Easier decision making

The Federal Highway Administration Intersection Statistics show a 90% reduction in fatalities, a 76% reduction in injuries and a 35% reduction in all crashes when comparing a roundabout to a traditional intersection

The South Dakota Strategic Highway Safety Plan (Pages 29-31) provides information on intersection crashes and proposals for several types of improvements and preventative measures to reduce crashes, injuries and fatalities - including roundabouts.

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