Exploring Optimal Signal Plans for Isolated Signalized Intersections with Central Pedestrian Refuges

Abstract

This paper addresses the global optimal signal plan of a fixed time control for an isolated signalized intersection with central pedestrian refuges considering both vehicle delays and pedestrian delays. A signal phase plan, a pedestrian signal setting scheme, and a signal timing plan are all part of the signal plan presented here. Pedestrian delays are explicitly formulated with signal timing parameters considering signal phase plans and pedestrian signal setting schemes. Integer nonlinear combinatorial programming models are proposed to minimize average and total delays. Numerical experiments show that the proposed optimization models outperform the existing ones, especially when traffic demands between phases are unbalanced. The analysis of the results shows that separate pedestrian signalization settings, and adjacent (or nonadjacent) allowed crossing phases for pedestrians at central islands are superior signal plan options when the minimum phase time is insufficient (or sufficient) to accommodate the minimum green time for crosswalks.