Variable speed advisory signals for linking coordinated systems in Canada

In the City of St. Albert, Alberta, Canada, variable speed advisory signals were installed in 1988 in order to improve the operation of a major roadway which connects the City of St. Albert with the City of Edmonton. These signals link two groups of signalized intersections operating under fixed time coordinated programs with different cycle times during most of the critical periods of the day. The influence of the speed advisory signals on traffic flow was evaluated in 1989. Delay and cyclic flow profile studies indicated that these signals had a positive effect on traffic flow. The paper describes the design and the operation of the speed advisory signal system and identifies the associated benefits and problems