Abstract :
Faced with an ever-increasing economic loss due to traffic congestion and accidents, the Metropolitan Toronto Authorities investigated the posibility of improving conditions through the use of a general-purpose digital computer to optimize in real time and on line the operation of traffic control signals. Following the successful conclusion of a small-scale pilot project, approval was obtained for a completely integrated system designed to incorporate some 1000 signals distributed in complex network formation througbout an area of some 240 square miles. Converting the concept into reality required the design and installation of a considerable amount of specialized equipment, such as vehicle detectors, together with the development and preparation of complex computer programs including both control and analysis routines. With the initial stages of this work more or less complete, testing of various control philosophis commenced, starting with the least sophisticated and gradually working up, while continually studying actual traffic conditions so that levels of performance could be judged. After four years´ effort, some 500 out of 850 existing signals are under computer control for an average of 15 hours every day, with the result that the time required to make any given journey has been reduced by an average of about 10 percent, even though the operational flexibility is still to some extent limited. A part from this major improvement, sufficient other benefits both direct and indirect have resulted from system operation to prove the validity of the original concept, especially on economic grounds. A conservative estimate indicates that, for a total capital outlay of some $5 million, wastage attributable to congestion and delay will be reduced by some $20 million per year.
