BRINGING A 40-YEAR-OLD TRAFFIC CONTROL SYSTEM UP-TO-DATE

Faced with an aging, costly traffic control system, the city of Cleveland is modernizing its 1950s-vintage system with a new economical, centralized system. Over the last several years, 25 to 30 percent of the existing system has failed at any given time. Traffic in the street network is controlled by a system of 92 fixed-time, predominantly two-phase, electromechanical traffic signal controllers that were installed in the 1950s. Criteria developed for the new system includes: Retrofitting new signal controllers and cabinets into the existing environment with the least disruption possible; Using existing underground ducts wherever possible to avoid extensive street disruption from new excavations; Existing overhead equipment should be incorporated into the new system; Timing plan changes and operations monitoring should take place at a central location; and Operating the new system needs to be accomplished within the constraints of the existing department structure.