Implementation of the Australian roundabout analysis method in SIDRA

Progress towards the development of a comprehensive Australian method for the analysis of capacity and performance of roundabouts is reported. The new Australian roundabout design guide to be produced during 1991 will include a significant revision of the current capacity analysis method by the incorporation of the results of Australian research. This method allows for the effects of circulating flows, entry flows and roundabout geometry on gap acceptance parameters. The new Australian roundabout analysis method will be implemented in the SIDRA package which was originally developed for signalised intersection analysis. As a computerised method, SIDRA will provide some significant advantages in the implementation of the capacity and performance analysis method for roundabouts. These include an iterative method to calculate circulating flows with capacity limitation for oversaturated approaches, and techniques for estimating entry lane flows, shared lane capacities and time-dependent delays.