Pulsating green wave (pugwa) is a control method which varies split, cycle time and offset by a modified gap/density control within a co-ordinated signal system network. The details of such a dual-mode system are explained. In the medium-sized west German city of Darmstadt (about 30 km south of Frankfurt) a study area with 10 junctions was defined and experiments were carried out with the following results: a) significant increase in journey speeds; b) improved journey times for buses; c) decrease of queue lengths to a minor level; and d) improvement of traffic safety (especially opposed-turn and rear-end collisions). The Darmstadt experiment chose not to employ a cost/benefit analysis and shows with a simplified test of effectiveness that pugwa is a valuable tool when traffic management measures of various kinds are implemented. A comparison with scoot shows differences which are discussed, although German and British philosophies in traffic control cannot be brought together at the present time. The alterations of the cycle time will be interpreted in the future with a new approach using synergetic theory. (A) This paper was also published in the journal, Traffic Engineering and Control (1988) 29 (7/8) 382-387, and for the abstract see also IRRD 814433.
Samenvatting