Design of Personal Rapid Transit Networks for Transit-Oriented Development Cities

Personal rapid transit (PRT) is an automated transit system in which vehicles are sized to transport a batch of passengers on demand to their destinations, by means of nonstop and non-transfer on its own right-of-way. PRT vehicles run exclusively on its tracks, called guideways. The guideways are designed as elevated facilities above the ground, for purpose of eliminating at-grade crossings or interferences with other transportation modes. In the recent planning practice for urban development in future, there has been an increasing and sustained emphasis in the global community in sustainable transportation systems. Transit-oriented development (TOD) has emerged as a promising alternative for sustainable communities by creating compact environments using convenient and efficient public transportation systems. To facilitate TOD development, an alternative to the personal car needs to provide a public transit mode which offers the same door-to-door flexibility at an acceptable cost. This could be achieved through a mixed design of high passenger-flows mass transit and flexible public transportation carrying low passenger-flows for the times or places. PRT is one of such flexible systems serving a supplement mode for the TOD development, where a PRT system functions as a local area network, connecting the traditional transit systems and other means of transit modes within its network. Two major downsides that restrict the PRT in the practical stage are the cost and line capacity. Both the cost and line capacity could be improved through an appropriate guideway network (GN) design, because a well-designed GN not only improves the connectivity and accessibility, but also provides more options in the route choice. This study investigates the methodology of PRT network design, to minimize both guideway construction cost and users’ travel cost. In particular it introduces a set of optional points, known as Steiner points, in the graph to reduce the guideway length. The model is formulated as a combined Steiner problem and assignment problem, and a Lagrangian relaxation based solution algorithm is developed to solve the problem. Numerical studies are carried on a realistic-sized network. The authors show the proposed model and solution algorithm can solve the PRT guideway network effectively.