Developing Passenger-Car Equivalents for Heavy Vehicles in Entry Flow at Roundabouts
Publication: Journal of Transportation Engineering
Volume 141, Issue 8
Abstract
This study develops passenger-car equivalents (PCEs) for heavy vehicles at roundabouts. For this task, the movements of cars and heavy vehicles were observed using video records collected from three roundabouts in Vermont; Ontario, Canada; and Wisconsin. The PCE was developed such that the variation in the entry capacity in a various mix of cars and heavy vehicles was minimized. The PCE was also applied to the prediction of the entry capacity using a roundabout capacity model. For the model inputs, the study adjusted the critical headway and the follow-up headway to account for the difference in driver’s gap acceptance behavior between cars and heavy vehicles. The result shows that the PCEs for heavy trucks and light trucks are 1.5–2.5 and 1.0–1.5, respectively, at the three roundabouts. In particular, the PCE for light trucks was lower than a default value of 2.0. The result also shows that the established model generally predicted the capacity more accurately when the critical headway and the follow-up headway were adjusted by different weights instead of the same weight (i.e., the default value of the PCE).
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Acknowledgments
The author thanks Mr. Moayed Naeem Khan, a former research assistant at the University of Windsor, for reducing the video data into numerical data in this study. The author also thanks Mr. Lee A. Rodegerdts at Kittelson & Associates, Inc., Mr. Egerton Heath at Region of Waterloo, Ms. Andrea Bill at the University of Wisconsin-Madison, and Mr. Patrick Fleming at Wisconsin Department of Transportation for providing the video records and geometric drawings used in the study. The author also thanks Dr. Zong Tian at the University of Nevada, Reno, for his advice on the maximum likelihood method. This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).
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Published In
Journal of Transportation Engineering
Volume 141 • Issue 8 • August 2015
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Feb 24, 2014
Accepted: Feb 20, 2015
Published online: Apr 21, 2015
Published in print: Aug 1, 2015
Discussion open until: Sep 21, 2015
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