Equilibrium Analysis of Low-Conflict Network Designs

Low-conflict network designs aim to reduce intersection delay by restricting or eliminating crossing conflicts. These designs range from alternating one-way street grids in central business districts to more radical designs that eliminate crossing conflicts altogether. However, travel distances in such networks are generally higher than in traditional networks. This paper proposes an equilibrium approach for evaluating the trade-off between increased distance and reduced intersection delay in networks of varying topology and demand patterns. To accomplish this objective, suitable link performance functions are developed to reflect different types of intersection control. Three control strategies are compared: two-way grids, one-way grids, and a vortex design with priority merges. These strategies are compared in grid networks, with analysis of sensitivity to demand levels and other parameters. The vortex-based design generally leads to lower average travel times and higher trip distances. However, at high demand levels the use of gap-acceptance formulas for priority merges with route choice; this union results in unstable, chaotic conditions.