Center for Traffic Simulation Studies

This paper presents the conceptual design and preliminary feasibility simulation results for a flexible transit system for travel from any point to any point based on real-time personalized travel desires. While it is demand-responsive, the concept is significantly different from older demand-responsive transit systems, which were often failures. The proposed system requires high coverage, refering to the availability of a large number of transit vehicles (often minibuses or vans) that could also operate in conjunction with private and paratransit systems. The design strictly eliminates more than one transfer for any passenger. The system could potentially provide a transit alternative that is much more competitive with personal auto travel than conventional transit systems due to significantly lower waiting times. The passenger demand for such a system is uncertain, but preliminary simulations show that under a variety of acceptable demand levels, the system can operate with high cost-effectiveness. This paper describes the concept in detail and offers arguments in favor of the system based on simulations. The system essentially attempts to solve a stochastic real-time passenger pick-up and delivery problem with a large number of vehicles. A strict optimization formulation and solution for such a problem is computationally prohibitive in real-time. The design proposed in this paper is effectively geared towards a decomposed solution using detailed rules that achieve vehicle selection and route planning. If real-time updates of probabilities is included, then this scheme can be considered as a form of quasi-optimal stochastic control.