Implementation of on-line zone control strategies for optimal ramp metering in the Minneapolis Ring Road

This paper presents the results from field implementation of gain scheduling in a feedforward/feedback zonal control system, in which sets of ramps along a freeway zone or section are controlled in a coordinated manner. An optimization algorithm determines the zone-optimal gains based on feedback from the performance of the closed-loop freeway system. Because the parameters, i.e., ramp rates adapt to traffic conditions in a closed loop, the new system is one step closer to being adaptive. The system is a practical alternative to advanced theoretical concepts of freeway corridor control, and can be integrated with gain scheduling currently available at traffic management centers