Traffic Volume Condition for Left-Turn Forbidden on Urban Road Unsignalized T-Intersection

To ensure main road traffic flow running smoothly, traffic volume condition for left-turn forbidden was analyzed. Defining equivalent people group to describe the non-motorized vehicles´ and pedestrians´ effect on vehicles, traffic flow priority of urban road unsignalized T-intersection was ranked renewedly, it was divided into five grades. Based on gap acceptance theory, potential capacity calculation models of each subordinate traffic flow were obtained. Taking prior traffic flow´s effects on subordinate traffic flow into consideration, movement capacity models of subordinate traffic flows were established. Based on the analysis above, traffic volume condition for left-turn forbidden was got, namely, when the left-turn traffic volume is larger than the left-turn capacity, it is needed to taking left-turn forbidden. Case study indicates that the capacity calculation methods and traffic volume condition for left-turn forbidden are accord with the traffic flow running reality.