A study of gap acceptance and turning movement capacity in Yangon

Abstract

Gap acceptance plays an important role in intersection design and signal warrant, and capacity calculation is the most essential part in unsignalized intersection analysis. This study investigates gap acceptance of drivers and turning movement capacity of uncontrolled intersections in Yangon, Myanmar. Three T-intersections were selected for study sites two intersections in the urban area and the other one in Yangon suburban region. As Yangon drivers drove on the right-hand side, the key movements that defined the intersection capacity would include left-turn from the major street (LTmajor), right-turn from the minor street (RT-minor), and left-turn from the minor street (LT-minor). Raff's method was applied to determine the gap acceptance for these three conflicting movements. The results showed that the longest gap acceptance for LT-minor ranged from 7 to 15 seconds. The shortest gap acceptance belonged to the RT-minor for 4 to 8 seconds. The gap acceptance at urban sites was shorter than that of suburban in all three movements. The drivers tended to decrease their gap acceptance when the traffic volume increased. However, the relationship between the gap acceptance and traffic flow was not significant. The Highway Capacity Manual approach was used to estimate the capacity for three turning movements. The findings approved that the capacity at these intersections mainly depended on the gap availability of major traffic flow. The capacity analysis based on the gap acceptance investigation would enable to get a better intersection design for Yangon.