RELATIONSHIP BETWEEN ROUNDABOUT GEOMETRY AND ACCIDENT RATES

This paper describes relationships between roundabout geometry and accident rates for one hundred roundabouts from throughout Queensland, Australia. Regression analyses are undertaken on "single vehicle," "approaching rear end," and "entering/circulating" accident categories. After various trials, it was found to be most important that accident models incorporate appropriate explanatory variables. The models described here were based on the concept of exposure and propensity, and on observed driver behavior. The driver behavior model developed in this study uses the 85th percentile speeds on each geometric element and the location of vehicle paths through the roundabout. The single-vehicle accident model includes traffic flow, length of driver path on the geometric element, 85th percentile speed on the previous geometric element, and radius of the geometric element. This model demonstrates the importance of limiting the difference between the expected drivers' speeds through successive geometric elements. The approaching rear-end vehicle accident model includes approaching and circulating traffic flow, and approach speed. This model demonstrates the importance of limiting the approach speed. Similarly, the entering/circulating vehicle accident model includes approaching and circulating traffic flow, and relative speed between entering and circulating vehicles. This model demonstrates the need to minimize the relative speed between entering and circulating vehicles. A brief discussion on the application of this research to other intersection types and roadways is given.

• Record URL:
  http://onlinepubs.trb.org/onlinepubs/circulars/ec003/toc.pdf
• 
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00978515
• Supplemental Notes:
  • The proceedings have been edited by the Texas Transportation Institute, Texas A&M University System, College Station, Texas. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • ARNDT, O K
  • Troutbeck, R J
• Conference:
  • International Symposium on Highway Geometric Design Practices
  • Location: Boston, Massachusetts
  • Date: 1995-8-30 to 1995-9-1
• Publication Date: 1998-1

Language

• English

Media Info

• Features: Figures; References;
• Pagination: p. 28:1-16
• Serial:
  • Transportation Research Circular
  • Issue Number: E-C003
  • Publisher: Transportation Research Board
  • ISSN: 0097-8515

Subject/Index Terms

• TRT Terms: 85th percentile speed; Behavior; Crash rates; Geometry; Mathematical models; Merging traffic; Rear end crashes; Regression analysis; Roundabouts; Single vehicle crashes
• Geographic Terms: Queensland
• Subject Areas: Data and Information Technology; Design; Highways; Planning and Forecasting; Safety and Human Factors; I21: Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure;

Filing Info

• Accession Number: 00794685
• Record Type: Publication
• Report/Paper Numbers: E-C003
• Files: TRIS, TRB, ATRI
• Created Date: Jun 12 2000 12:00AM