Changing Traffic Lights Green
by Officer Jack Handy
Many traffic lights in medium and large cities are equipped with censors that allow law enforcement and emergency vehicles to change them from red to green immediately. These are called traffic light preemption censors. they are the little black boxes you often see sitting on top of the traffic light pole http://www.skyoptics.com/images/traf...%20372x333.jpg and http://www.tomar.com/products/j7/209...
by Officer Jack Handy