Abstract
It is a common practice that VMS (Variable Message Sign) is implemented on the network with alternative routes to achieve optimal traffic allocation among the alternative routes. But VMS has its own limitation. That is, desirable traffic allocation among alternative routes cannot be automatically achieved by the VMS information itself. Rather it is generally known that VMS information generally causes overreaction and concentration problem. Considered is a simple hypothetical network with two alternative routes, one bypass and the other with a physical bottleneck. The concentration problem is illustrated with this sample network. And strategic VMS control is proposed to compensate for the discrepancy between the system optimal and the predicted traffic allocations. To make this control concept work, a new concept and the estimation procedure for the dynamic capacity are provided especially for congested flow condition. Finally, functional requirements for VMS control with overreaction and concentration problem are summarized, which remains for further research.
