Comparative Evaluation of Statistical Methods for Critical Gap Estimation: A Case Study of U-Turns at Uncontrolled Median Openings in India

Abstract

Gap acceptance and the lateral positioning of vehicles are vital factors that affect U-turn behavior at uncontrolled median openings in urban areas. Accurately determining the critical gap at these intersections is crucial for analyzing queue lengths, delays, and overall capacity, while also aiding safety assessments. The critical gap for a U-turn driver is the minimum time needed to merge into the main traffic flow. As a statistical measure, it cannot be directly observed. The maximum likelihood method is the most widely used technique for estimating this gap. This study focuses on U-turn driver behavior and estimates the critical gap using the maximum likelihood and modified Raff's methods based on data collected from four median openings in Bhubaneswar, India.