Turbo Roundabouts: Informational Primer

Details

• Corporate Creators:
  United States. Department of Transportation. Federal Highway Administration
• Corporate Contributors:
  United States. Department of Transportation. Federal Highway Administration. Office of Safety
• Subject/TRT Terms:
  Geometric Design Highway Capacity Highway Safety Roundabouts Traffic Safety
• Publication/ Report Number:
  FHWA-SA-20-019
• Resource Type:
  Tech Report
• Right Statement:
  Public Domain
• Geographical Coverage:
  United States
• Corporate Publisher:
  United States. Department of Transportation. Federal Highway Administration
• Abstract:
  Implementing modern roundabouts saves lives and reduces serious injuries resulting from intersection and intersection-related crashes. As planned points of conflict, crashes attributed in some way to intersections contribute significantly to traffic fatality and injury numbers in the United States. Approximately half of all crashes and half of fatal and serious injury crashes occur at or near intersections. In the single year of 2018, 8,858 people were killed in intersection and intersection-related crashes. In stark contrast, there were a total of 46 fatalities at roundabouts built in the United States over the nine-year period spanning 2005 to 2013, a time period in which the total number of roundabouts in the United States grew from a few hundred to a few thousand. At the individual intersection level, converting a traditional at-grade signalized intersection to a modern roundabout is expected to reduce the number of injury crashes by 78 percent. Converting a traditional at-grade minor-road stop control intersection to a modern roundabout is expected to reduce the number of injury crashes by 82 percent. Though most roundabouts in the United States are single-lane, multilane roundabouts have become more common. There is a tendency for some 2 x 2 multilane roundabouts1 to experience higher than expected frequencies of sideswipe – same direction crashes. Given that modern roundabout geometry reduces both the speed and angle of collisions, the sideswipe – same direction crashes in 2 x 2 multilane roundabouts tend to be low severity (i.e., crashes in which people are not injured, but where vehicles may be damaged). Some other countries have implemented a modified version of a multilane roundabout, the turbo roundabout, with positive results. Characteristics of the turbo roundabout could potentially be effective at influencing driver behavior and reducing lane change conflicts in a way that would address the crash types occurring in 2 x 2 multilane roundabouts. First designed and implemented in the Netherlands in the 1990s, the turbo roundabout (shown in figure 1) has the same general operating characteristics as modern roundabouts but utilizes notably different geometrics and applications of traffic control devices. This informational primer seeks to describe the characteristics of turbo roundabouts, highlighting the design and traffic control features, operational capabilities, and potential safety benefits of these roundabout alternatives.
• Format:
  PDF
• Collection(s):
  Federal Highway Administration
• Main Document Checksum:
  urn:sha-512:8f2945bbe24c63e7668019dbe9f12ec007b41251b3fbc6525bc4205f199078268a79e8134622cd67b9819fd0e35e5ccb6b1448694df89bbe123183a3b1afa12e
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/88317/dot_88317_DS1.pdf
• File Type:
  [PDF - 5.44 MB ]