Gap Acceptance Cycles for Modelling Roundabout Capacity and Performance

Aerial photograph of road


Gap-acceptance theory has been used widely for estimation of capacity at unsignalised roundabouts and two-way sign-controlled intersections. This paper discusses the use of the gap-acceptance method beyond modelling capacity. The author has developed gap acceptance capacity and performance models by signal analogy, including the estimation of delay, queue length and stop rates for roundabouts and other unsignalised intersections. These models have been implemented in the SIDRA INTERSECTION software which has been in extensive use in traffic engineering practice. This paper will describe the basic method that uses gap acceptance cycles for modelling performance measures with a focus on the modelling of queue length at roundabouts. A simple single-lane roundabout example is given to explain important aspects of modelling the queue length.


AKÇELIK, R. (2018). Gap Acceptance Cycles for Modelling Roundabout Capacity and Performance. Presentation for the paper in: Roundabouts as Safe and Modern Solutions in Transport Networks and Systems (Eds E. Macioszek, R. Akçelik and G. Sierpi_ski). Proceedings of the 15th Scientific and Technical Conference, Transport Systems Theory and Practice. Department of Transport Systems and Traffic Engineering, Faculty of Transport, Silesian University of Technology, Katowice, Poland, pp 89-98.

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