A Study on the Impacts of Right-Turn Flows on Capacity of Motorcycle Lanes at 3-Leg Intersections

This study utilized traffic flow microsimulation assimilation to gather information about the traffic conditions adjacent to the right-turn links of 3-leg intersections. To determine the flow states of the main roads in the vicinity of the right turn lane from local roads or alleys, VISSIM micro-simulation models were employed. The study considered different cases of turning path radii and built flow-density relationship curves to evaluate the effect of varying levels of intrusion of the branch flow into the main road on motorcycle capacity. According to the research, a mid-block motorcycle lane can have a theoretical capacity of 8,963 vehicles per hour. Based on the study, it is recommended that: 1) If right turn volume reaches about 1,000 MCU/hour, vehicles should follow the curb radius of R8m; 2) If turning traffic is within 600 MCU/hour, it is acceptable for vehicles from the branch road to encroach onto the main road by only 0.875–2.625m; 3) Road marking of lane lines should be used to prevent right turn vehicles from encroaching further into the main road, particularly at intersections with right turn traffic exceeding 300 MCU/hour; 4) If turning volume is over 1,000 MCU/hour, dedicated right turn lanes should be built.