Monrovia, California: Emergency Vehicle Preemption and Visual Warning System

Excerpt from Federal Highway Administration Publication:

In the spring of 2001, the city of Monrovia, California (population 37,000), equipped 10 signalized intersections with a highly advanced traffic signal preemption system. Called the Emergency Vehicle Early Warning Safety System, or E-ViEWS, it combines signal preemption with visual warning and communications capabilities. Emergency vehicles are equipped with satellite-linked transponders that track their position and movements. When a vehicle in emergency response mode approaches an intersection equipped with the early warning system, the traffic lights change to give it the right-of-way. Illuminated warning signs mounted above the intersection display flashing icons that show motorists the direction of the emergency vehicle's approach. All of Monrovia's police cars, fire trucks, and ambulances are now equipped with the transponders that allow them to trigger the warning signs.