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...

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Bibliographic Details
Published in:	Transportation research record Vol. 2436; no. 1; pp. 81 - 91
Main Authors:	Torbic, Darren J., Donnell, Eric T., Brennan, Sean N., Brown, Alexander, O'Laughlin, Mitchell K., Bauer, Karin M.
Format:	Journal Article
Language:	English
Published:	Los Angeles, CA SAGE Publications 01-01-2014
Subjects:	Criteria Dynamic tests Dynamics Friction Horizontal Simulation Transportation Vehicles
Online Access:	Get full text
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Summary:	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 super elevation 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.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0361-1981 2169-4052
DOI:	10.3141/2436-09