THE CELL TRANSMISSION MODEL - A DYNAMIC REPRESENTATION OF HIGHWAY TRAFFIC CONSISTENT WITH THE HYDRODYNAMIC THEORY

This paper presents a simple representation of traffic on a highway wi th a single entrance and exit. The representation can be used to predi ct traffic's evolution over time and space, including transient phenom ena such as the building, propagation, and dissipation of queues. The easy-to-solve difference equations used to predict traffic's evolution are shown to be the discrete analog of the differential equations ari sing from a special case of the hydrodynamic model of traffic flow. Th e proposed method automatically generates appropriate changes in densi ty at locations where the hydrodynamic theory would call for a shockwa ve; i.e., a jump in density such as those typically seen at the end of every queue. The complex side calculations required by classical meth ods to keep track of shockwaves are thus eliminated. The paper also sh ows how the equations can mimic the real-life development of stop-and- go traffic within moving queues.