DESIGN OF INTERSECTIONS ON DIVIDED HIGHWAYS

Current design policies used in the United States do not provide clear guidance on the effect of median width on the traffic operations and safety of at-grade intersections on multilane divided highways. This paper examines the relationship of the median width and median opening length to intersection operations and safety by means of accident analyses, field observational studies, and traffic operational modeling. The research results indicate that at rural unsignalized intersections, the frequency of both accidents and undesirable driving behavior decreases as the median width increases. Conversely, at suburban unsignalized intersections, the frequency of accidents and undesirable driving behavior increases with increasing median width. Delay at signalized intersections also increases with increasing median width. Based on these results, the paper provides guidance on the selection of appropriate median widths for signalized and unsignalized intersections on divided highways in rural and suburban areas. Multilane divided cross sections are frequently used by highway agencies for major nonfreeway facilities in rural and suburban areas. The multilane cross section enables the highway to operate between intersections with a capacity (under ideal conditions) approaching that of a freeway. The presence of a median provides a physical separation between the vehicles traveling in opposite directions and reduces accident rates below the levels found on undivided highways. At-grade intersections represent one of the major sources of traffic operational and safety problems on multilane divided highways. Turning volumes are generally larger at intersections than at driveways and midblock median openings, and accidents tend to cluster at locations where the turning volumes are highest. This paper examines the effect of two key geometric design parameters - median width and median opening length - on the operations and safety of divided highway intersections. Both signalized and unsignalized intersections are considered.

• Record URL:
  http://onlinepubs.trb.org/onlinepubs/circulars/ec003/toc.pdf
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• 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:
  • Harwood, D W
  • Pietrucha, M T
  • Fitzpatrick, K
  • Wooldridge, M D
• 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; Tables;
• Pagination: p. 29:1-14
• Serial:
  • Transportation Research Circular
  • Issue Number: E-C003
  • Publisher: Transportation Research Board
  • ISSN: 0097-8515

Subject/Index Terms

• TRT Terms: At grade intersections; Behavior; Divided highways; Field studies; Highway operations; Highway safety; Length; Median openings; Medians; Multilane highways; Rural areas; Signalized intersections; Suburbs; Traffic crashes; Traffic delays; Traffic models; Unsignalized intersections; Width
• Subject Areas: Design; Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors; I21: Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure;

Filing Info

• Accession Number: 00794686
• Record Type: Publication
• Report/Paper Numbers: E-C003
• Files: TRIS, TRB, ATRI
• Created Date: Jun 12 2000 12:00AM