Performance Analysis of large scale PRT networks: theoretical capacity and micro-simulations

The individual, on-demand and non-stop transportation service of Personal Rapid Transit (PRT) is expected to attract a significant share of private car users - in particular when installed as a dense network in congested urban areas. For this reason, transportation planners are concerned that the demand for PRT could exceed its carrying capacity. It is therefore of primary interest to estimate the effective transport volume that a PRT network could possibly handle in large scale networks. Of particular concern is the “performance gap” of PRT: the difference between theoretical performance limits and effective vehicle flows observed in micro-simulations of large scale PRT networks. The main objective of this paper is to quantify this performance gap and to suggest improvements. We clearly distinguish between the line capacity and the boarding-capacity of off-line stations, with focus on the latter. We present new analytical solutions for station capacities while considering various control alternatives. The analytical capacities are compared to results from particular small and large scale micro- simulations. Based on the results we can make qualified suggestions at various PRT control levels which allow bringing the performance in large scale PRT networks closer to the capacity limits.