ASSESSMENT OF CURRENT SPEED ZONING CRITERIA

As early as 1947, studies concluded that the majority of drivers ignore speed limits and drive at speeds that they believe are safe and reasonable. Since then, some studies have supported this conclusion whereas others indicated that speed limits do affect travel speeds in varying degrees. In an FHWA-sponsored assessment of current speed zoning criteria, speed and accident data were collected at 50 locations, both urban and rural, in four states on roadways with posted speed limits ranging from 25 to 55 mph. These data were analyzed to determine travel speed characteristics, compliance with posted speed limits, and the point of minimum accident risk. Significant findings were as follows: Mean speeds exceeded posted speed limits by 1 to 8 mph; 85th-percentile speeds ranged from 6 to 14 mph over the posted speed limit, or 4 to 7 mph over the mean speed; the majority (70.2%) of free-flow drivers observed did not comply with posted speed limits; in general, 85% compliance was achieved at speeds 10 mph over the posted speed limit; accident rates for the 25-mph zones were consistently much higher than for any of the other zones; and the speed at which accident risk was minimized occurred at the 90th percentile of the travel speeds observed.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1990/1281/1281-005.pdf
• Record URL:
  https://scholar.google.com/scholar_lookup?title=ASSESSMENT+OF+CURRENT+SPEED+ZONING+CRITERIA&author=D.+Harkey&author=H.+Robertson&author=S.+Davis&publication_year=1990
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/030905060X
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1281, Human Factors and Safety Research Related to Highway Design and Operation. 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

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  Washington, DC  United States  20001
• Authors:
  • Harkey, David L
  • Robertson, H Douglas
  • Davis, Scott E
• Publication Date: 1990

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 40-51
• Monograph Title: HUMAN FACTORS AND SAFETY RESEARCH RELATED TO HIGHWAY DESIGN AND OPERATION 1990
• Serial:
  • Transportation Research Record
  • Issue Number: 1281
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: 85th percentile speed; Compliance; Crash rates; Data collection; Field studies; Hazards; Risk assessment; Rural areas; Speed limits; Speed zones; Urban areas
• Uncontrolled Terms: Criteria
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors; I73: Traffic Control; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 00603695
• Record Type: Publication
• ISBN: 0-309-05060-X
• Files: TRIS, TRB, ATRI
• Created Date: Feb 28 1991 12:00AM