This article describes MOTION, a new prototype system for the automatic control of traffic signals, under the global goal of optimised traffic flows and delays in a road network. MOTION (Method for Optimisation of Traffic Signals in Online Controlled Networks) is designed to operate either by itself or under a supervisory management system. Its basic idea is to combine the advantages of well-designed 'green waves' for major traffic streams in a network, with the flexibility of the immediate response of local signals to actual traffic conditions. Its model optimises all signal-setting program components: (1) cycle time; (2) offset; (3) structure; and (4) split. Its system distinguishes three functional levels: (1) strategic, setting up basic network control for the next 10-15min; (2) tactical, allowing minor structural control adaptations cycle by cycle; and (3) operational, handling random traffic effects second by second. It can also assign special priority to public transport vehicles. Although MOTION so far exists only as a prototype system, its first tests in a small network in Cologne, Germany in 1995 had very encouraging results, resulting in improved flow conditions and decreased pollutant emissions and fuel consumption by 8-15%.
Abstract