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Prioritization of traffic signal preemption requests received from multiple sources over different communication mediums

  • US 9,478,131 B2
  • Filed: 01/08/2010
  • Issued: 10/25/2016
  • Est. Priority Date: 01/08/2010
  • Status: Active Grant
First Claim
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1. A method for prioritizing multiple candidates for preemption of a traffic signal phase at an intersection, comprising:

  • receiving a respective light signal transmitted from one or more light-signaling vehicles approaching an intersection, each respective light signal encoding a priority code using a first set of values and representing a respective light-emitter-based preemption request;

    receiving a respective radio signal from one or more radio-signaling vehicles approaching the intersection, each respective radio signal encoding respective location data and encoding a respective priority code using a second set of values, the encoded priority code representing a respective radio-transmitter-based preemption request;

    adding a respective preemption candidate to a set of preemption candidates for each light-emitter-based preemption request;

    adding a respective preemption candidate to the set of preemption candidates for each radio-transmitter-based preemption request;

    determining a respective relative priority of each preemption candidate based on the priority code of each preemption candidate;

    outputting a request for preemption of the traffic signal phase for a preemption candidate having a highest priority;

    wherein the outputting of the request for preemption makes the preemption candidate in-progress;

    iteratively checking the set of preemption candidates for a preemption candidate eligible for outputting for preemption of the traffic signal phase;

    starting a hold timer and assigning a hold status to the in-progress preemption candidate in response to the in-progress preemption candidate not being in the candidate set in the checking step;

    canceling the hold timer and hold status in response to the in-progress preemption candidate being in the candidate set in the checking step; and

    selecting a preemption candidate from the set of preemption candidates for outputting for preemption of the traffic signal phase in response to expiration of the hold timer.

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