Thugs and fires are obvious threats for police and firefighters, but traffic accidents also pose a serious danger for these first responders.

Nearly 13 percent of the firefighters and police officers who die in the line of duty are killed in vehicle-related incidents, and fire trucks are involved in ten times as many collisions as other heavy trucks.

University of Arizona researchers have teamed up with the Maricopa County Department of Transportation, or MCDOT, in an effort to radically lower these statistics by creating a system that will make intersections safer for emergency responders and the general public.

They are installing a prototype at six intersections in Maricopa County at Anthem, Ariz., north of Phoenix, and will test it this summer, according to Larry Head, of the UA College of Engineering's systems and industrial engineering department, and Faisal Saleem, MCDOT Intelligent Transportation Systems branch manager.

Their efforts are part of a national push to create smart vehicles that communicate with one another and with traffic control systems. In 2013, the National Highway Traffic Safety Administration, which mandates seatbelts for all cars and trucks, may require every vehicle sold in the United States to be equipped with this technology, which could nearly eliminate rear-end collisions, red-light running and left-turn smashups.

The system being installed in Maricopa County could be one of the first steps in deploying a smart-vehicle system throughout the country, Head said. "There's the question of which comes first, the intelligent cars or the infrastructure to support them," he said. "If we install a system for emergency vehicles, it could be the core infrastructure and the pathway to deployment. As the nation's public and private vehicle fleets are renewed, this system could lead the way in making intersections safer."

The MCDOT intersections at Anthem will be equipped with dedicated short-range communications radios. Daisy Mountain Fire District trucks, Maricopa County REACT vehicles and some transit vehicles also will carry the short-range radios. All the vehicles will be tracked by GPS.

REACT stands for Regional Emergency Action Coordinating Team. It provides traffic management on arterial roads in Maricopa County, and coordinates the efforts of multi-agency and multi-jurisdictional fire trucks, ambulances, police cars and EMT vehicles.

When one or more emergency vehicles approach an intersection, one will be given a green light, while other vehicles in the area will be held up until the intersection is clear. Each vehicle also will be in contact with other responders and will know their exact locations, Head explained.

By contrast, the systems installed at most intersections today fall far short of this. The signals communicate with emergency vehicles by infrared light and the first vehicle in the area pre-empts the signal. Flashing white lights above the signals show that a preempt signal has been received, but that just means there's an emergency vehicle in the area. If two or more responders are approaching an intersection, they're not aware of one another or if the signal is being preempted for them or someone else, Head noted. This can lead to serious collisions.

In addition to smart control at intersections, the system will allow emergency vehicles at the scene to broadcast their locations so other vehicles not involved in the incident will know which lanes are closed and can select alternate routes to reach other emergencies or to find a clear corridor to hospitals. If additional emergency vehicles are heading for the incident, they will be able to find the fastest routes through traffic.

The vehicles also will communicate with the Arizona 511 network to alert motorists to the traffic problems, allowing them to select alternate routes. This will help cut down on congestion and prevent secondary accidents that often occur when distracted motorists are faced with traffic disruptions.

"Our tests of this system will significantly advance the technology and make intersections safer for emergency responders," Saleem said. "We also hope it will improve response times where seconds can mean the difference between life and death."

Local school buses will participate and be equipped with short-range radios to test the system for transit priority. "If you have a bus that's behind schedule, you can have the traffic light hold the green longer or give an early green," Head explained. "If they're running on time, they can go with the normal stream of traffic." Tying transit vehicles to the system could make public transit more attractive because the vehicles would run on time more often.

The UA researchers and Maricopa County also plan to adapt the system to freeway entrance ramps that are controlled by traffic signals. "If we have a two-lane ramp, you can hold one lane red and turn one green to let everyone go, clearing the way for the emergency vehicle," Head said. "On one-lane ramps, you can just turn the light green and flush out the cars to clear the way."

The big question with ramp control -- and, in fact, in all this work -- is driver behavior, Head noted. "There is a big human factors problem to be solved to get intelligent vehicles properly integrated with drivers," he said. The UA researchers have had an ongoing program since the early 1990s of analyzing traffic video to determine how drivers respond to various situations. They will continue to look at driver behavior when testing the system on freeway entrance ramps. Currently, they're considering tests of the system on the eastbound side of I-10 at Warner Road in Tempe.

Head, who has been working on intelligent traffic design since 1992, says the systems are getting a lot smarter. He's excited about the tests in Maricopa County, which are to run until Sept. 1. The equipment is being installed, and software will be set up in April and May, with tests beginning toward the end of the summer.

The partnership between Maricopa County's Department of Transportation and UA's Systems and Industrial Engineering Department has been vital in bringing the intelligent traffic control system to life.

"Our universities have so much talent and can give a lot of benefit to public agencies by doing this kind of applied research," Saleem said.

"This partnership has been really good for us," Head added. "Without a real agency to bring this technology into the real world, we would just be off doing research we think is interesting, but the benefits might never reach the public."