Using microsimulation and crashes to evaluate the safety of left turn lanes at rural signalized intersections

Left turn movements at intersections can be particularly unsafe. One treatment aimed at making the movement safer is the provision of left turn lanes. However, there is a missing piece in the related research, specifically how the length of left turn lanes impacts the safety of intersections. The Ministry of Transportation Ontario (MTO) has defined this as a high priority research topic. There were two major objectives in this research, both of which were addressed with microsimulation. The first was to determine a relationship between a length of left-turn lanes and safety performance of an intersection, and second was to examine the combined impact of simultaneous installation of left turn lanes with varying lengths and protected left-turn signal phasing. The findings suggested that the longer a left turn lane is, the safer the intersection would be, especially with regard to rear-end crashes.