TRAFFIC SIGNAL CONTROL SYSTEMS MAINTENANCE MANAGEMENT PRACTICES (FINDINGS OF NCHRP SYNTHESIS TOPIC 27-11)

With an increasing number of traffic signal systems, and therefore an increasing number of signalized intersections, maintenance management has become an important issue. Public agencies are responsible for systems that are growing in size and complexity while staffing and resources are shrinking. Thus, it becomes increasingly difficult to provide for proper maintenance of equipment within their jurisdictions. The purpose of this paper is to present a summary of the findings of National Cooperative Highway Research Program (NCHRP) Synthesis 245 which is an update to NCHRP Synthesis 114. Synthesis 245 re-examines current traffic signal control maintenance management practices in light of the extensive use of solid state equipment, personal computers, and integrated systems. Synthesis 114, which updated a previous publication from 1974, focused on the transition in maintenance requirements and practices as the hardware evolved from electromechanical to solid-state design. Full computer control of traffic signal systems was not particularly common in 1984. Consequently, since the publication of Synthesis 114 in 1984, many changes have occurred in the technology and maintenance of signal systems. Maintenance managment practices have, therefore, also changed. In Synthesis 245, it is emphasized that computers are integral to the operation (and maintenance) of traffic signal systems. Since Synthesis 114, new types of technologies have been implemented to improve the state of traffic signal control. In addition, Intelligent Transportation Systems (ITS) have been developed and are being deployed throughout the country for surveillance and control of traffic signal systems. Systems are increasing in magnitude and complexity at an increasing rate, resulting in a need for greater amounts of funding and more employees with higher skill levels than were previously required. These issues can be offset by the use of computers that permit the accumulation of maintenance information into databases, from which information can be selected and processed to assist in making cost effective management decisions.