Advancing Turbo Roundabouts in the United States: Synthesis Report

Details

• Creators:
  Porter, Richard J. ; Gooch, Jeff ; Chestnutt, Catherine ; Moore, B. ; Broeren, P. ; Tigelaar, J.
• Corporate Creators:
  VHB/Vanasse Hangen Brustlin, Inc.
• Contributors:
  Shaw, Jeffrey
• 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-19-027
• Resource Type:
  Tech Report
• Right Statement:
  Public Domain
• Geographical Coverage:
  United States
• Edition:
  Synthesis Report
• Contracting Officer:
  Shaw, Jeffrey
• Corporate Publisher:
  United States. Department of Transportation. Federal Highway Administration. Office of Safety
• Abstract:
  A turbo roundabout has the same general operating characteristics as modern roundabouts but utilizes notably different geometrics to address conflicts associated with common crash types in multilane roundabouts. International experience suggests turbo roundabouts are adaptable to the U.S. context, providing an effective roundabout solution for higher-volume intersections. The goal of this document is to synthesize existing published resources (e.g., reports, papers, presentations, videos, and tools) on the topic of turbo roundabouts from international and domestic sources. The synthesis has three major sections: 1) geometric design, 2) capacity and operational performance, and 3) safety performance. The synthesis provides specifics regarding the treatment of various users, including motorists, pedestrians, cyclists, heavy vehicles, and motorcyclists. The synthesis also includes sections on education and public outreach approaches targeting non-technical audiences. The geometric design of a turbo roundabout is governed by the horizontal swept path of a design vehicle and a fastest path analysis for a passenger car. Key geometric designs include selection of turbo roundabout type and determination of functional combinations of the inner radius, cross section elements, and spirals within the turbo block. Turbo roundabout capacity is dependent on type but is generally similar in magnitude to modern multilane roundabouts. Methods in the HCM 2010 produced reasonable estimates of turbo roundabout capacity in Poland. Research available to-date also indicates that, with smaller radii and raised lane dividers, the reduced vehicle speeds and elimination of weaving in a turbo roundabout is expected to produce fewer and less severe crashes than multilane roundabouts and significantly fewer and less severe crashes than other traditional control types.
• Format:
  PDF
• Funding:
  DTFH61-16-D-00005L
• Collection(s):
  Federal Highway Administration
• Main Document Checksum:
  urn:sha-512:9c29bc5356a1bf4498a4a9acf1f915db3cf9b728476fea15d4bc9294b7f1b3296570abe46f2f4a4d4518111c7bba3202bb3e44c88694a47abc5f2c645c51b9ec
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/88316/dot_88316_DS1.pdf
• File Type:
  [PDF - 5.25 MB ]