emergency signalWhat is the purpose of the small white and blue light located on the traffic signal support?
Some traffic signals are equipped with an emergency vehicle pre-emption device which allows an emergency vehicle (usually fire trucks and ambulances) to activate a green signal in the direction they are travelling. The white and blue light is used by emergency vehicles as an indication that the pre-emption is active. During an emergency preemption, several emergency vehicles may approach an intersection from different directions. The white light indicates which emergency vehicle has priority going through the intersection.
