TRAFFIC SIGNAL PREEMPTION FOR EMERGENCY VEHICLES:
A CROSS-CUTTING STUDY

The sudden appearance of an emergency vehicle en route to an emergency can be extremely disruptive to nearby vehicles as individual drivers maneuver to get out of the way. Some drivers become confused and create conflicts that can cause emergency vehicle crashes or block lanes increasing response times. Using Intelligent Transportation Systems to provide emergency vehicles a green light at intersections can reduce driver confusion, reduce conflicts, and improve emergency response times.

This cross-cutting study identifies issues associated with emergency vehicle operations and emergency vehicle preemption.

Putting the “first” in “first response.”
A U.S. Department of Transportation Study: FHWA-JPO-05-010

Fairfax County, Virginia

As of 2004, Fairfax County was in the process of equipping selected corridors within a large, highly integrated regional traffic signal system.

Plano, Texas

Plano, Texas has a 20-year history of operating EVP across 100 percent of its signals, which were equipped incrementally as part of a comprehensive growth plan.

St. Paul, Minn.

St. Paul has over 25 years of operating experience across 100 percent of its signals, which were equipped retroactively as part of a multi-year EVP deployment plan.

Executive Summary

This study reports information gathered during a review of publications and site visits to three jurisdictions operating emergency vehicle preemption systems. The purpose of this study is to increase awareness among stakeholders—including police, fire, rescue and emergency medical services (EMS)—about the benefits and costs of emergency vehicle preemption. Benefits of emergency vehicle preemption systems include the following:

• Emergency vehicle preemption has allowed Fairfax County, Virginia to reduce its response times. The system permits emergency vehicles along U.S. 1 to pass through high volume intersections more quickly with fewer conflicts, saving 30 to 45 seconds per intersection.

• Emergency vehicle preemption in the City of Plano, Texas has dramatically reduced the number of emergency vehicle crashes – from an average of 2.3 intersection crashes per year to less than one intersection crash every five years.

• In addition, due to reduced delays at signalized intersections, the City of Plano can achieve the same response times with fewer fire/rescue and EMS stations than would normally be required, providing significant cost savings. The city has maintained a response time goal achievement rate of over 90 percent, contributing to its Insurance Services Office Class 1 Fire Suppression Rating – the highest possible rating on a scale from 1 to 10.

• Emergency vehicle preemption installed in St. Paul, Minnesota has permitted police, fire/rescue, and EMS vehicles to reach the scene of an incident faster and with a reduced chance of a crash. Crash rates per emergency vehicle responses were dramatically reduced in the years following deployment.

This study also identifies major lessons learned to guide others in achieving similar benefits. The following list highlights some of these elements critical to successful emergency vehicle preemption deployment.

• Emergency vehicle preemption systems can benefit many stakeholders, including police, fire/rescue, EMS, and transit operators (if transit signal priority is also provided). To make sure that the needs of all these stakeholder groups are met, it is important to involve all stakeholders in a formal and collaborative manner.

• A champion, be it an individual or an organization, is often key to success. At all three sites visited, the preemption initiative progressed when one person or one group of people provided leadership and sponsorship of the effort. In some cases, a different stakeholder took the role of champion as the initiative progressed. Therefore, it is important that the role of champion is clearly identified throughout the process.

• Stakeholders should consider emergency preemption as part of a developing local ITS architecture. In doing so, it may be possible to leverage funding for the emergency vehicle preemption system by sharing costs with other ITS-based emergency response, congestion management, and clean air attainment programs. Broader stakeholder groups and a wider range of funding options increase the potential for successful deployment.

• Signals near emergency facilities (i.e., hospitals, trauma centers, and fire/rescue and EMS stations) will be preempted more often than others and drivers may experience delays if multiple preemption events occur during a short period of time. Each of the sites indicated that the public accepted these delays and that a public awareness campaign highlighting the public safety benefits of preemption was a key factor in reducing preemption-related complaints.

• It is critical to identify one agency that is responsible for system maintenance. A clear method for reporting system problems and well known lines of communication among all involved is required to avoid delay in making any necessary adjustments or repairs. Effective maintenance programs ensure that the system provides the highest degree of benefit.

• A green light is not guaranteed. Emergency vehicle drivers need to use caution not to over-rely on the system and need to be prepared to stop if provision of the preemption phase is delayed (i.e., awaiting time out of an in-progress pedestrian phase). Emergency vehicle preemption operation and limitations must be a part of initial and recurring emergency vehicle driver training.

The purpose of this study is to enable 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.

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