Pedestrians have a significant influence on vehicular capacities of turning movements at signalized intersections. The increasing emphasis on pedestrian traffic has brought to light deficiencies in the relevant research in China. It is imperative to accurately quantify the effect of pedestrians on the vehicular capacity to provide a basis for traffic operations and facility designs in mixed traffic conditions. This study proposes an analytical model for the capacity of right-turn movements influenced by pedestrians at signalized intersections. The model takes into account pedestrian behavior, pedestrian-vehicle conflict mechanisms, and pedestrian arrivals in platoons. The conflict zone capacity is modeled based on the conflict mechanism. The model was calibrated and used as the basis to calculate the right-turn vehicular capacities. The capacities yielded by the proposed model depend strongly on the average conflict times. The results show that pedestrians have a strong impact on the right-turn capacities at low pedestrian volumes, and that the effects of additional pedestrians decrease as the pedestrian volumes increase. VISSIM was employed to simulate the interactions between right turns and pedestrians to validate the model. A numerical example is presented to compare the proposed model with the simulations and several existing analytical models. The comparisons indicate that Highway Capacity Manual (2000) predicts the smallest effect of pedestrians on the right-turn capacities. At low pedestrian volumes, the predictions of the other methods are approximately equal; at high pedestrian volumes, the models assuming pedestrian priority yield lower capacities than those assuming no priority.
Abstract