Optimization of vehicle delay and drivers’ unhappiness at a signalized network: a multi-objective approach

In existing system-optimal traffic-responsive signal strategies, the individual driver’s interest is always neglected. In order to make a compromise between user equilibrium (individual delay) and system optimality (total delay), a traffic signal scheduling strategy with consideration of drivers’ un-happiness is firstly developed based on the cell transmission model (CTM). The exponential function is adopted to delineate the driver’s anxiety according to their waiting time, which leads to the assignment of the traffic signals is dominated by drivers’ waiting time but not the total volume demand. By adopting the discrete harmony search algorithm (DHS), numerical simulation results illustrate the effectiveness of our real-time traffic light scheduling. Secondly, in order to satisfy the trade-off between the proposed cost (drivers’ unhappiness) and the common traffic performance (network delay), a bi-objective urban traffic light scheduling problem by minimizing both the drivers’ unhappiness and the total network delay is proposed, which is solved by the non-dominated sorting genetic algorithm II (NSGA-II) and non-dominated sorting harmony search algorithm (NSHS). Experiments are carried out to compare the efficiency of both algorithms.