Interplay of behavior and traffic dynamics at U-turn slots

Abstract

Driver behavior often complicates the modeling of U-turns slots. Using a modified Nagel-Schreckenberg model for paired U-turn slots, we simulate traffic at different conditions by varying the inflow rate p_in and outflow rate p_out, and for different probabilities p_u that a car that is entering the system will make a U-turn. We observe that congestion cascades from the inner lane to the adjacent lane due to the insistence in making a U-turn despite the presence of a long queue. We found transition points p_u* on when this congestion occurs. The minimum obtained value is p_u*=0.25± 0.05 which appears at high p_in and p_out. The results of our study can be a potential guide to designing U-turn slots while considering the traffic volume of vehicles that will make a U-turn.