Roundabout Corridors - A Study in Performance and Efficiency

Roundabouts are being recognized as an intersection control strategy that fulfills the goals of sustainability, complete streets, context-sensitive design, and improved public safety. In the last few years, highway agencies have constructed several arterials using roundabouts in series rather than traffic signals. While the agencies have reported success, there has been no comprehensive peer-reviewed research to document the performance and efficiency of this strategy using roundabouts in series on an arterial rather than traffic signals. Anecdotal and limited research has indicated significant safety improvements. However, detailed mobility performance studies addressing measures of travel time, average speed, and delay are lacking. Highway agencies do not have complete research to assist them in analyzing the differences between a roundabout corridor and a signalized corridor with a reasonable level of efficient progression and intelligent transportation system (ITS) support. The need and interest for highway agencies to select roundabouts in series is increasingly compelling. One of the critical issues is design liability. Without regard to travel efficiency, safety research has consistently shown that traffic signals have six to nine times the injury crash rate compared to a roundabout. In some states and municipalities where design immunity is minimal, the liability of selecting a traffic signal for intersection control over a roundabout is increasingly a concern. Several states and municipalities and at least one Canadian province have roundabout-first policies. A literature search found few documents related to efficiency of roundabouts in series on an arterial. However, there are several corridors where roundabouts in series are in design and construction phases to support a research effort. There are several corridors where a series of five of more have already been completed. Their locations are diverse and important to arterial performance research. Locations include Waterloo, Ontario; San Diego, California; and some arterial routes on the New York State Department of Transportation system. Several roundabout corridors are in the stages of design. These will be ripe for research.  The objective of the research is to compare the performance of arterials with traffic signals to arterials with roundabouts. The performance of traffic signal systems is well researched, and many software models exist to provide this study with good material. Field research on roundabouts in series would be conducted in several established locations. It is suggested that arterial corridors with three, or preferably four or more consecutive roundabouts be studied. All modeling would be field calibrated using no less than four roundabout arterials. The research would report both on the level of accuracy of the models as well as on the performance measures and data collected from field studies.  The use of roundabouts in series is rapidly expanding, and performance information is lacking. The lack of national research on performance is requiring agencies to conduct their own individual analysis at their expense, and often at a lower level of research quality. Lacking comprehensive research, some agencies are not selecting roundabout strategies because they lack information regarding the overall efficiency of such strategies.


  • English


  • Status: Completed
  • Funding: $300000.00
  • Contract Numbers:

    Project 3-100

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Sundstrom, Lori

  • Performing Organizations:

    Kittelson and Associates

    1818 Library Street, Suite 500
    Reston, VA  United States  20190
  • Principal Investigators:

    Rodegerdts, Lee

  • Start Date: 20110428
  • Expected Completion Date: 0
  • Actual Completion Date: 20131231
  • Source Data: RiP Project 26457

Subject/Index Terms

Filing Info

  • Accession Number: 01470729
  • Record Type: Research project
  • Source Agency: National Cooperative Highway Research Program
  • Contract Numbers: Project 3-100
  • Files: TRB, RiP
  • Created Date: Jan 26 2013 1:00AM