Study Details

Study Title: Safety Impacts of a Modified Right Turn Lane Design at Intersections

Authors: Schattler and Hanson

Publication Date: JAN, 2016

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. The authors of this paper are involved in funded research to study the impacts of the modifications, utilizing a driver behavior analysis and a crash-based safety evaluation. The driver behavior field investigations, which included both a comparative test and control analysis at ten sites, and a before and after analysis at three sites, indicated that line of site and approach angle was improved due to less drivers requiring exaggerated head turns to complete the right turn, less roll and go stops, and more vehicles stopping at the stop bar when a stop was required. Additionally, the crash-based safety analysis, using the Empirical Bayes method revealed statistically significant reductions in total intersection crashes and right turn related crashes at the subject approaches after the modifications were made. Based upon 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 related crashes.

Study Citation: Schattler, K. and T. Hanson. "Safety Impacts of a Modified Right Turn Lane Design at Intersections". Presented at the 95th Annual Meeting of the Transportation Research Board, Paper No. 16-0790, Washington, D.C., (2016).

CMFs Associated With This Study

Category: Intersection geometry

Countermeasure: Improve angle of channelized right turn lane

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.558 44.2 4 Stars All All Not specified Not specified
0.564 43.6 3 Stars All K,A,B,C Not specified Not specified
0.411 58.9 4 Stars Other All Not specified Not specified
0.397 60.3 4 Stars Right turn,Other All Not specified Not specified

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