Automatic control of variable message signs in the interurban Scottish highway network

The paper presents the design, implementation, and evaluation work performed by a European consortium for the development of a Variable Message Sign information and guidance system in the interurban Scottish highway network. The control strategy employed is based on simple automatic control concepts with both feedback and feedforward terms subject to user-optimum constraints. Feedforward terms are employed for the prediction of travel times and delays along long-distance interurban highway links. Simulation studies demonstrate the potential improvements achievable with these kinds of control measures and control strategies. The implementation concepts and field evaluation results are outlined.