Lane Utilization Analysis of Shared Left-turn Lane Based on Saturation Flow Rate Modeling

Lane utilization analysis is an essential task in the planning and design stage of signalized intersections and arterials. This task becomes difficult to perform satisfactorily when shared permissive left-turn lane is present. It allows leftturners to proceed into the intersection together with conflicting pedestrians and usually results in unequal lane utilization by through traffic. To address this complex matter, a four-stage based saturation departure process from shared left-turn lane is proposed based on empirical analysis. Then it is incorporated into lane flow distribution procedure for lane utilization estimation. The case study shows that equal flow ratio principle by the proposed saturation flow rate modeling provides a better representation of traffic distribution than that of Highway Capacity Manual and equal lane volume strategy by Japan Society of Traffic Engineers manual. The consistent results of delay estimates assist in emphasizing the importance of saturation flow rate estimation also for performance evaluation.