HIGHWAY ALIGNMENT AND SUPERELEVATION: SOME DESIGN-SPEED MISCONCEPTIONS

Horizontal alignment and superelevation of curves have an impact on the traffic safety performance of highway sections. Research that relates traffic safety to roadway horizontal alignment has consistently shown that traffic accidents increase with increasingly sharper curves. Sharp curves in segments that otherwise have good alignment tend to surprise drivers and create even more hazardous situations. Consistency in design speeds along significant sections of highways has been advocated by some as a means of controlling the incidence of surprise curves in otherwise gentle alignments. However, design speeds for horizontal curves are a function of the maximum superelevation policies adopted by a design agency. Therefore, a single curve design may be regarded as having different design speeds by agencies that have different maximum superelevation policies. For this reason, the use of resign-speed criteria for identifying potentially hazardous horizontal alignments would not appear to be appropriate. This finding is discussed in relation to the resurfacing, restoration, and rehabilitation projects proposed by the American Association of State Highway and Transportation Officials.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1980/757/757-005.pdf
• Record URL:
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• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Operational Effects of Geometrics. 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
• Authors:
  • Haywood, John C
• Conference:
  • 59th Annual Meeting of the Transportation Research Board
  • Location: Washington District of Columbia, United States
  • Date: 1980-1-21 to 1980-1-25
• Publication Date: 1980

Media Info

• Media Type: Print
• Features: References; Tables;
• Pagination: pp 22-25
• Monograph Title: Facility design and operational effects
• Serial:
  • Transportation Research Record
  • Issue Number: 757
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Alignment; Design speed; Hazards; Highway curves; Superelevation; Traffic crashes; Traffic safety
• Uncontrolled Terms: Hazard perception; Horizontal alignment
• Subject Areas: Design; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure;

Filing Info

• Accession Number: 00325985
• Record Type: Publication
• ISBN: 0309030714
• Files: TRIS, TRB
• Created Date: May 21 1981 12:00AM