Superelevation Design for Sharp Horizontal Curves on Steep Grades

The objective of this study was to develop superelevation criteria for sharp horizontal curves on steep grades. Field studies were undertaken and vehicle dynamics simulations (point mass, bicycle, and multibody) were performed to investigate combinations of horizontal curve and vertical grade design criteria. The vehicle dynamics simulations used AASHTO design criteria and field-measured data to investigate the safety margins against skidding and rollover for several vehicle types on sharp horizontal curves with steep grades. Research results indicated that for a simple horizontal curve, the maximum rate of superelevation should not exceed 12% on a downgrade. A spiral curve transition is recommended if the maximum superelevation rate is greater than 12%. On upgrades of 4% and greater, the maximum superelevation rate should be limited to 9% for minimum-radius curves under certain conditions. The superelevation attained at the point of curve entry should be checked and compared with a lateral friction margin condition so that the lateral friction margin on curve entry is not less than the margin within the curve. On multilane highways, the "Stay in Lane" sign should be installed in advance of sharp horizontal curves on steep downgrades.

• Record URL:
  https://doi.org/10.3141/2436-09
• Availability:
  • Find a library where document is available. Order URL: http://www.trb.org/Main/Blurbs/171937.aspx
• Authors:
  • Torbic, Darren J
  • Donnell, Eric
  • Brennan, Sean N
  • Brown, Alexander
  • O’Laughlin, Mitchell K
  • Bauer, Karin M
• Publication Date: 2014

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 81–91
• Monograph Title: Highway Design 2014, Volume 1
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Issue Number: 2436
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Field studies; Highway curves; Highway design; Highway grades; Road downgrades; Simulation; Superelevation; Upgrades (Roads); Vehicle dynamics
• Uncontrolled Terms: Steep grades
• Subject Areas: Design; Highways; I20: Design and Planning of Transport Infrastructure;

Filing Info

• Accession Number: 01516024
• Record Type: Publication
• ISBN: 9780309295345
• Report/Paper Numbers: 14-4501
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Feb 26 2014 12:40PM