A Review of Gap-Acceptance Capacity Models

Gap-acceptance capacity models apply to the analysis of minor movements at two-way stop and give-way (yield) sign-controlled intersections, entry streams at roundabouts and opposed (permitted) turns at signalised intersections. The same modelling principles apply to all these cases with different model parameters representing the intersection geometry, control and driver behaviour at different traffic facilities. This paper presents a review of some well-known analytical models that use bunched exponential and simple negative exponential distribution of headways in the opposing stream. Different bunching models are considered including the latest model used in SIDRA INTERSECTION. The capacity estimates from different models are compared. Research recommendations are included. The paper includes a survey method for follow-up headway and critical gap parameters.