Multi-Objective Optimization of Traffic Signal Settings for Isolated Intersections Considering Efficiency as well as Safety

Abstract

Pedestrian and vehicle conflicts at signalized intersections may result into serious injuries or even deaths. Many pedestrian signal phasing schemes exists in order to improve pedestrian safety. Leading pedestrian interval is such a phasing scheme to give pedestrians a head start to establish their presence at the crosswalk before conflicting movements are released. This paper evaluates the relative applicability of leading pedestrian interval (LPI),with respect to a commonly used phasing scheme i.e. concurrent pedestrian phase (CPP), by solving an optimization problem considering both efficiency and safety. Efficiency and safety indices are converted into monetary values to choose the more suitable pedestrian phase pattern simultaneously with optimal signal parameters under given input. The optimization problem consists of nonlinear objective function as well as nonlinear constraints. Therefore, it is difficult to obtain optimal solution using traditional nonlinear programming techniques. Hence, population-based heuristic optimization algorithms can be used to solve the problem in reasonable time.