Unsignalized intersection capacity and level of service: Revisiting critical gap

Operational performance at a minor street stop-controlled intersection is a function of motorist gap acceptance behavior. Issues in modeling gap acceptance are reexplored using discrete choice methods. Logit models of varying levels of sophistication are used in simulation to generate average delays at the intersection stop bar. Comparison of simulated and empirical delays suggests that deterministic methods for modeling gap acceptance may represent a reasonable trade-off between accuracy and ease of application, but two potential concerns are at issue - namely, delay estimates are very sensitive to the value used for mean critical gap, and the use of a single-valued critical gap necessitates the exclusion of disaggregate factors influencing the gap acceptance decision. Logit models estimated for intersection traffic movements have identified a number of such influential factors. Further research to explore fundamental issues of gap acceptance should be undertaken before adopting a capacity and level-of-service methodology for minor street stop-controlled intersections.