A New Roundabout Capacity Survey Method

This presentation gives a summary of a new method for conducting roundabout capacity surveys using detailed vehicle trajectory data developed under funding by SIDRA SOLUTIONS. The method observes gap acceptance cycles based on the traffic signal analogy concept developed by Dr Rahmi Akçelik for modeling roundabout entry lane capacity. Unlike previous methods, this method derives estimates of key gap acceptance parameters (follow-up headway and critical headway) and blocked and unblocked times (virtual red and green times) at the same time as roundabout entry lane capacity. The new method based on observation of gap acceptance cycles allows application of gap acceptance surveys at all levels of demand flows. The survey method is proposed for use in calibration of roundabout and two-way sign control capacity models in particular. It is applicable to all gap acceptance situations including permitted turns, unsignalised bypass lanes and right turn on red at signalized intersections.

Full presentation Poster as well as the Sections of the Poster in individual slides are included in the zip folder. Full paper for Transportation Research Record is under review.