New York City Department of Transportation (NYCDOT) took an exhaustive look in 2016 at the problem of left turn pedestrian and bicyclist injuries and fatalities in New York City. It was studied with querying five years from 2010 to 2014 of citywide crash data which consisted of 1,105 crash reports drawn from the most problematic locations citywide, and 478-intersection analyses where treatments were installed. The study relies on these findings to provide recommendations for additional engineering, planning, and education efforts to prevent and mitigate left turn failure to yield pedestrian and bicyclist injuries. Because they were based on crash report, detailed comparative analysis using field video data is necessary to support those findings in the crash study and extend current left-turn tool box at approximately 13,000 signalized intersections in New York City.

Left turn movements have induced more conflict points with pedestrians and vehicles but have also created adverse impacts to traffic operations.  During the permitted phase drivers should find a safe gap for opposing vehicles and conflicting pedestrians in the middle of the intersection. Therefore, as safety improvement measures, many signal or movement control policies such as a full or partial exclusive signal phase for turning vehicle and/or pedestrian movements as well as left-turn prohibitions have been introduced to reduce vehicle-vehicle and vehicle-pedestrian conflicts. Signal timing plans with exclusive left turn phases constraint capacity of traffic and pedestrian movements while left-turn prohibitions cause detours and may transfer traffic impacts to other intersections.

The purpose of this paper is to evaluate effective safety measures and elements for left turn movements at signalized intersections by performing a comparative video analysis on trajectories and speeds, gap time and headway of left-turning vehicle and conflicting pedestrians during the permitted and protected phases. Understanding driver behaviors during both phases and related pedestrian-vehicle, and vehicle-vehicle interactions will help to identify appropriate left-turn control guidelines and designs at signalized intersections and develop effective control policies to provide safe and more efficient environment for pedestrians and vehicles.