How to Run an Automated Transportation System

The synchronous longitudinal guidance (SLG) approach to allocating guideway space and controlling traffic in a ground transportation network is described in this paper. The transportation system considered is one in which completely automated vehicles follow deterministic position-time profiles during their travel through the network. The key feature in the SLG approach is a dynamic scheduling algorithm which allocates guideway space to vehicles in such a way that the capacity of critical points (or bottlenecks) in the network is not exceeded. This guarantees that traffic flows smoothly through the entire network and that queues are confined to the entrances. Two scheduling algorithms are Identified in this paper. The basic slot allocation algorithm used in processing vehicle trip requests is outlined first. Then the more general cycle allocation algorithm, which is suitable for control of large networks, is described. The results of a computer simulation of a network run using the latter algorithm are summarized, and the required auxiliary SLG functions of entrance and exit control, merge control, and safety assurance are discussed briefly.