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Signal Preemption Systems
System Operation
Fire Truck
Emergency Vehicle Preempting a Signal
 
A traffic signal preemption system is an electrical device or devices that allow a traffic control signal to respond uniquely to the approach of a particular type of vehicle or the occurrence of an unusual condition at or near a highway intersection. Such systems are designed to increase safety, reduce emergency response times and enhance public transit operations.

A signal mounted preemption system requires the installation of receiving device within the traffic control signal cabinet that responds to a remote triggering device attached to specific authorized vehicles. These systems may be used for the preemption of normal traffic control signal operation by the approach of emergency vehicles, or may be used to modify the length of the green light time to allow for more efficient transit operation. Signal mounted systems generally allow vehicles traveling in the same direction as the emergency vehicle or bus to receive, or continue to receive, a green indication. In the case of emergency vehicle preemption, the green indication provides an opportunity for motorists to clear the road ahead of the advancing emergency vehicle. For signal mounted systems, if the remote signal from the source is interrupted or terminated for any reason, normal traffic control signal operation will continue. Signal mounted systems may respond to different vehicles or types of vehicles in recognition of different vehicle priorities.
 
Installation and operation of signal mounted systems are at the discretion of the traffic control signal owner. Emergency providers and transit companies must make specific application for authorization to own and operate remote signaling devices.  To apply, the agency or company should provide the information requested on the appropriate form below and submit it to the ODOT Region where the system will be operating. The Region Traffic Manager will review the request and submit a recommendation to the State Traffic Engineer. The State Traffic Engineer has approval authority for all requests.
 
For more information, contact the Traffic Operations Unit, Traffic Operations and Engineering Section, Oregon Department of Transportation, at 503-986-3589.
 

Resources
 
Emergency Vehicle Preemption Request Form
 
Bus Transit Priority Request Form
 
Railroad Preemption Design and Operation - A guide for determining design and operation criteria related to railroad preemption at signalized intersections.