Estimation of Crash Modification Factors for an Adaptive Traffic-Signal Control System
Publication: Journal of Transportation Engineering
Volume 142, Issue 12
Abstract
Adaptive traffic-signal control (ATSC) is a traffic management strategy in which traffic-signal timings change, or adapt, based on observed traffic demand. Although ATSC can improve mobility, it also has the potential to reduce crashes because mainline stops should be reduced. This paper aims to evaluate the safety effectiveness of ATSC using the empirical Bayes method. This analysis examines 47 urban or suburban intersections where ATSC was deployed in Virginia using 235 site-years of before data and 66 site-years of after data. Installing ATSC was found to produce a crash modification factor (CMF) for total intersection crashes of 0.83 with a standard error of 0.05. This CMF was statistically significant at a 95 percent confidence level. Fatal and injury crashes did not change by a statistically significant amount, indicating that the primary safety benefit of ATSC was reduction in property damage crashes. Analyses of ATSC safety effects by crash type, by traffic volume level, and by operational improvement magnitude were also performed. All crash types were found to be reduced, but safety benefits varied from corridor to corridor and by volume levels. It was concluded that ATSC installation can potentially reduce total crashes at highway intersections and that public agencies should consider ATSC’s safety and mobility benefits when justifying ATSC projects.
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Information & Authors
Information
Published In
Journal of Transportation Engineering
Volume 142 • Issue 12 • December 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Oct 20, 2014
Accepted: Apr 29, 2016
Published online: Jul 15, 2016
Published in print: Dec 1, 2016
Discussion open until: Dec 15, 2016
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