Emergency Response...Safety at Controlled Intersections a High Priority

December 9, 2011

Imagine, for a moment, you are at the intersection of East Main Street and South Memorial Drive. You are the fifth car in the line, the light is red and an ambulance and fire engine are approaching from the rear with red lights, siren and air horn blaring. There are cars to your left, right and in front of you. No one knows which way the emergency responders want to go and the crossing traffic is unaware of the approaching emergency response vehicles. What is your next move? If you move, are you going to pull your vehicle into the path of the emergency vehicle? If you remain stationary, is someone going to hit you vehicle in an attempt to clear a path? This is an all too familiar scene that is played out too often at intersections around the city.

If you recall, there was an article by Teresa Lee, in January of this year that announced the City would install an Emergency Vehicle Preemption System. This system is 100% reimbursable to the City of Prattville, thanks to a 2010 Congressional Appropriations Act. The article mentioned that the system allows Fire Department emergency vehicles to preempt traffic signals while responding to emergency calls. This, in turn, will decrease response times to emergencies and the danger of accidents to responders and the public by preempting the traffic signal to give the emergency vehicle the right of way. This will decrease the number of times that you find yourself in the situation mentioned above.

How does it work? A GPS receiver like any other, on-board the emergency unit, uses Department of Defense (DOD) satellites to determine position, speed and heading. The information gathered is transferred, by radio signal, to the upcoming intersection. The system sends a priority request, from the vehicle to the controller cabinet at the intersection, for green light priority through normal controller functions. The system communicates the vehicles latitude, longitude, speed and estimated time of arrival to the intersection. Regardless of whether the approaching emergency vehicle is a slow moving ladder truck of fast moving ambulance, the system communicates real-time information to determine the appropriate actions to give right-of-way for that vehicle at that intersection at that moment. The interruption to the normal flow of traffic is minimized while the speed and safety of emergency response is greatly improved.


Seventeen of the cities intersections have already been equipped with this GPS technology and the City Engineer's office has been trained in its operation. Training has also been completed for the emergency vehicle equipment installation. Prattville Fire Department is currently in the process of installing the equipment on eleven of its emergency response vehicles. We plan to go live with this time and life-saving technology by the first of January 2012.

Here is the demo we conducted today: