Proposed Geometric Features to Improve Safety of Modern Roundabouts

Modern roundabouts were found to improve safety and reduce overall delay at intersections. However, roundabouts were also found to increase potential risks for cyclists. Due to the deflection at entry, cyclists may lose control of their vehicles. In addition, other vehicles may cut-off on cyclists while entering or exiting the roundabout. Due to the above factors, as well as other factors, many before-after studies found an increase in traffic collisions involving cyclists after the conversion of conventional intersections into roundabouts. Another concern associated with the installation of roundabouts is the safety of pedestrians, especially blind or limited-sighted persons who find difficulty in negotiating roundabouts. Those safety concerns resulted in some studies to suggest the installation of traffic signals at roundabouts, which runs counter to the basic engineering premise of effective non-interrupted traffic operations at roundabouts. This paper provides new geometric features that have the potential to increase the safety of both cyclists and pedestrians at roundabouts. The paper evaluates the operational and safety impacts of those new proposed features. A simple model is provided to determine the operational and safety characteristics where the new features might be warranted. An application example is also provided to quantify the safety benefits versus the costs.

• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Dabbour, Essam
  • Easa, Said M
• Conference:
  • Transportation Research Board 85th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2006-1-22 to 2006-1-26
• Date: 2006

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Figures; References; Tables;
• Pagination: 14p
• Monograph Title: TRB 85th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

• TRT Terms: Automobiles; Crashes; Cyclists; Pedestrian safety; Roundabouts; Traffic circles
• Uncontrolled Terms: Bicycle safety; Roundabout design
• Subject Areas: Bridges and other structures; Highways; Pedestrians and Bicyclists; I20: Design and Planning of Transport Infrastructure;

Filing Info

• Accession Number: 01031623
• Record Type: Publication
• Report/Paper Numbers: 06-1699
• Files: TRIS, TRB
• Created Date: Aug 24 2006 7:41AM