TEC Engineering

A common problem for emergency vehicles is delay encountered at signalized intersections due to red lights and traffic congestion. Even if the vehicles are using lights and sirens, even if the other drivers try their best to clear a path, there may be nowhere to go if the light is red and the approach is already congested.

To combat this problem, systems have been developed to alter the traffic signal timing to favor the emergency vehicle. Such systems, called Emergency Vehicle Preemption, detect the approach of the emergency vehicle and make adjustments to the traffic signal to help clear a path. After the emergency vehicle has passed, the traffic signal quickly returns to normal operation.

System Types
Two types of emergency vehicle detection technology are currently available. One type uses sonic sensors to detect standard emergency vehicle sirens. A second type detects light from a special emitter mounted on authorized emergency vehicles. In the case of Colerain Avenue, there is use by a variety of emergency vehicles. In addition to the local Colerain Township police and fire, many of the outer suburban district emergency vehicles may pass through on their way to hospitals or other points to the south. Therefore, the type of system which detects sirens was chosen, and no special emitter equipment is needed on the vehicle.

White Lights
The system includes small white signal lights on each detected approach to each intersection. These lights communicate the status of the system to the emergency vehicle driver and to the public.

The signal lights normally remain dark, but are energized when the system detects an emergency vehicle, to let drivers know the system is responding. A flashing white light means that the system has detected an emergency vehicle approaching in that direction. A steady white light means that, although the system has detected the vehicle in that direction, it is responding to another emergency vehicle on another approach. This situation calls for special caution, since two emergency vehicles may meet at an intersection.

The signal lights go dark after the emergency vehicle has cleared the intersection, and the signal operation returns to normal.

Comments? Questions?
Because this is a test installation, the project team is anxious to hear from the public about any problems or issues which might develop. If you own property abutting Colerain Avenue, own or manage a business in the affected area, or simply use Colerain as a driver or pedestrian, we would like to hear any comments or observations you may have. We are particularly concerned about increasing delays on side streets when the traffic signal timing favors emergency vehicles on Colerain Avenue.