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Title:Effectiveness Evaluation of a Modified Right-Turn Lane Design at Intersections
Author(s):Schattler, Kerrie L.; Hanson, Trevor; Maillacheruvu, Krishnanand
Subject(s):right-turn lane design
channelized right-turn islands
traffic crashes
safety evaluation
crash modification factor
empirical Bayes
safety performance functions
crash causation analysis
driver behavior
head-turn angles
Geographic Coverage:Peoria, Illinois, metro area
Abstract:From 2006 to 2014, ten right-turn approaches in the Peoria, Illinois, area were selected and reconstructed with a modified right-turn lane design. The major purpose of the modified design was to improve the line of sight for passenger vehicles attempting to turn right, while also accommodating semi-tractor trailer trucks. While the actual changes varied among intersections, the final result at each was an improvement to the approach angle for right-turning vehicles stopped to view cross traffic. Bradley University researchers were involved in a two-part study in which they (1) performed site-specific effectiveHanness evaluations of the modified sites, and (2) conducted a crash causation analysis of right-turn crashes at 116 sites in Illinois to identify geometric design variables that correlate with right-turn crashes. In the site-specific evaluation, driver behavior analyses and traffic crash–based safety analyses were performed to assess the safety performance of the modified right-turn lane design. The field investigations of driver behavior, which included a comparative “test and control” analysis at ten sites, indicated that line of site and approach angle was improved; specifically, fewer drivers had to make exaggerated head turns to complete the right-turn, there were fewer roll-and-go stops, and more vehicles stopped at the stop bar when a stop was required. Additionally, the crash-based safety evaluation, using the empirical Bayes method, revealed statistically significant reductions in crashes at the subject approaches (59.0%) and the targeted crash type, right-turn crashes at the subject approaches (59.6%) after the modifications were made. Based on these results, it is recommended that improving the right-turn approach angle by reducing the skew of the right-turn approach be considered as a safety measure for sites experiencing right-turn crashes in Illinois. The results of the crash causation analyses revealed significantly higher right-turn crashes for approaches with head-turn angles greater than 140, right-turn angles less than 45, and acute intersection angle less than 75. Recommendations on the characteristics of good candidate sites for the installation of the modified right-turn lane design in Illinois are presented in this report.
Issue Date:2016-06
Publisher:Illinois Center for Transportation/Illinois Department of Transportation
Citation Info:Schattler, Kerrie L., Trevor Hanson, and Krishnanand Maillacheruvu. 2016. Effectiveness Evaluation of a Modified Right-Turn Lane Design at Intersections. Illinois Center for Transportation Series No. 16-013. Research Report No. FHWA-ICT-16-012. Illinois Center for Transportation, Rantoul, IL.
Series/Report:Illinois Center for Transportation Series No. 16-013
Research Report No. FHWA-ICT-16-012
Genre:Technical Report
Sponsor:Illinois Department of Transportation, R27-111
Rights Information:No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.
Date Available in IDEALS:2016-06-06

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