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.