Introduction
A key issue facing localities in the U.S. is the challenge that rapid growth in populated areas places on the fire/rescue and EMS community. Constrained by tight budgets, officials must make decisions on how to provide appropriate levels of service while at the same time coping with increasing demand for services and increasing congestion levels.
Emergency vehicles (EVs) operating in higher congestion levels are at higher risk for involvement in crashes and are subject to unpredictable delays in reaching the scene of a fire or crash. One means to offset the effects of congestion is the installation of emergency vehicle preemption (EVP) equipment at signalized intersections. This ITS technology provides a special green interval to the EV approach while providing a special red interval on conflicting approaches.
The concept of EVP and the potential benefit of preemption control to support emergency response is nearly as old as the traffic signal itself. In 1929, the American Engineering Council published Street Traffic Signs, Signals, and Markings,1 which included a subsection Emergency Control in the section on Street Traffic Signals: "In any coordinated system supplemental arrangements may be provided for breaking the system into small units for emergency operation, such as runs of fire apparatus."
Over the years, various concepts have been developed to provide the emergency control described in the 1929 document. Several systems were deployed that created a pre-programmed "green wave," providing a progressive green display for the EVs based on the station of dispatch, the response location, and the use of pre-determined emergency response routes.
In the late 1960s, technologies became available to provide emergency control using vehicle-based emitters and signal-based detectors that allowed the EVs to preempt the signals as they were approached. Many communities invested in these systems in an effort to reduce the number of EV crashes. Some cities committed to the deployment of EVP on 100 percent of their signals, retrofitting hundreds of signals and including the technology on all new ones. Other growing communities committed to the technology early in their growth cycles and integrated EVP on every new signal as the community grew.
The material presented in this cross-cutting study is derived primarily from two types of sources: written sources and interviews. Interviews were conducted at three sites — Fairfax County, Virginia; Plano, Texas; and St. Paul, Minnesota — that were selected to show a wide range of EVP deployment options, including jurisdiction size, scope of EVP deployment, jurisdictional responsibilities, and the use of the system by police and transit. Individuals interviewed include local policy makers, fire chiefs, transportation and traffic engineers, fire/rescue and EMS vehicle drivers, police officers, and signal system technicians. This study includes a summary of the experience for the three sites with regard to the benefits experienced, costs incurred, and lessons learned.
The purpose of the study is to enable other jurisdictions to benefit from the composite experience of others in an effort to reduce the time required to move from a good idea to real improvements in the delivery of emergency services.
1American Engineering Council (1929). Street Traffic Signs, Signals, and Markings.