INVESTIGATION OF CURRENT AND PROPOSED SUPERELEVATION DESIGN PRACTICES ON ROADWAY CURVES

A common feature of curve design standards of the United States, Germany, and the United Kingdom is designers' freedom in applying above-minimum values for curve radii. On the basis of research findings suggesting a strong dependence of operating speed on degree of curve, it appears that, if consistency rules are not applied, this freedom may result in unrealistic assumptions for operating speed, with potential implications for safety. In addition, a comparison of the assumed values of the side friction coefficient (f) with empirical data for f-values "acceptable" by drivers confirms that, even for minimum-radius curves, actual operating speeds are underestimated for design speeds below 90 kph (56 mph). Innovative approaches to curve design suggest that, in addition to the incorporation of explicit consistency rules in design guidelines, the link between curvature and speed should be taken into account. A design procedure reflecting the association between curvature and speed, as well as enabling simplification of the superelevation - curvature relationship, is suggested in this paper and compared to existing design guidelines. It is suggested that the advantages and disadvantages of reconsidering design values for the f coefficient could be discussed at a future stage.

• 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

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  Washington, DC  United States  20001
• Authors:
  • KANELLAIDIS, G
  • Dimitropoulos, I
• 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. 20:1-12
• Serial:
  • Transportation Research Circular
  • Issue Number: E-C003
  • Publisher: Transportation Research Board
  • ISSN: 0097-8515

Subject/Index Terms

• TRT Terms: Curvature; Design practices; Design speed; Design standards; Highway curves; Highway safety; Operating speed; Superelevation
• Uncontrolled Terms: Side friction coefficient
• Geographic Terms: Germany; United Kingdom; United States
• Subject Areas: Design; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure;

Filing Info

• Accession Number: 00794677
• Record Type: Publication
• Report/Paper Numbers: E-C003
• Files: TRIS, TRB, ATRI
• Created Date: Jun 12 2000 12:00AM