Positioning of left-turn lanes

High left-turn accident rates at intersections with opposing left-turn lanes may be caused by inadequate sight distance. The availability of sight distance is related to the positioning of left-turn vehicles at the intersection. In this research, the behavior of left-turn drivers during the permitted left-turn phase was filmed. From the film, the positioning of left-turn vehicles was recorded. The sight distance available to each left-turn driver was computed at these study sites. Also, the gap acceptance of the left-turn drivers was investigated. The results of the study showed that left-turn drivers position their vehicles in such a manner as to achieve adequate sight distance. A relationship among left-turn accident rates, availability of sight distance, and gap acceptance was also found. A set of guidelines for the positioning of left-turn lanes which provide adequate sight distance was developed from the results of this study