Crash Patterns and Potential Engineering Countermeasures at Maryland Roundabouts

Each year in the United States more than 1.2 million injuries and 9,000 deaths occur in highway traffic accidents at intersections. Previous research has found that construction of roundabouts in place of traditional intersections can decrease collision frequency and severity. Despite these safety benefits, some traffic accidents still occur at roundabouts. The present study reviewed police crash reports for a set of roundabouts in Maryland to develop a typology of crashes and identify potential countermeasures. The review included 149 collisions at 29 single-lane roundabouts and 134 collisions at 9 double-lane roundabouts. Most traffic accidents involved only property damage. One common crash pattern at both single- and double-lane roundabouts involved vehicles colliding with the central island, which accounted for almost half of all single-vehicle run-off-road crashes. Other major accident types included rear-end and sideswipe collisions. About three-quarters of all collisions occurred at entrances to roundabouts. Based on review of crash reports and visits to several roundabouts, high approach speeds were an important driver crash factor, and some drivers may not have seen the roundabout in time. Increasing the conspicuity of upcoming roundabouts through larger “roundabout ahead” and “yield” signs could reduce speeds by alerting drivers ahead of time, especially at night. Enhanced landscaping of central islands as well as reflective pavement markers and “yield” signs at the entrance to roundabouts also could help drivers recognize roundabouts and the need to yield to circulating traffic. Certain design features (e.g., entry deflection on approach roads) also may aid in reducing speeds.


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Media Info

  • Media Type: Web
  • Features: Figures; References; Tables;
  • Pagination: 21p

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Filing Info

  • Accession Number: 01105030
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 10 2008 3:28PM