SAFETY IMPACTS OF INCREASING LENGTHS OF LEFT-TURN LANES

摘要

Left-turn lanes can improve the safety and operation of intersections by providing space fordeceleration and storage of turning vehicles. The length of the lane is critical in the design ofleft-turn lanes. Insufficient length may result in left-turn lane overflow which seriously impactsthe safety of the intersection. The objective of this research is to determine the safety impacts ofincreasing storage lengths of the left-turn lanes. To achieve the objective of this research, fieldstudy was conducted at the intersections with and without overflow problem, with differentgeometric, signal timing, and traffic flow conditions. Two approaches were employed todetermine the safety benefits of increased storage lengths of left-turn lanes: 1) crash dataanalysis, and 2) simulation-based safety analysis. The research concludes that extending thelength of left-turn lane to eliminate the left-turn lane overflow problem can significantly reducethe risk of rear-end crashes.