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

• Current Assignee: Global Traffic Technologies LLC (Vontier Corp.)
• Original Assignee: Global Traffic Technologies LLC (Vontier Corp.)
• Inventors: Eichhorst, Kevin
• Primary Examiner(s): SMALL, NAOMI J
• Application Number:
  US12/684,442
• Publication Number:
  US 20110169661A1
• Time in Patent Office: 2,482 Days
• Field of Search: 340/906
• US Class Current: 1/1
• CPC Class Codes: G08G 1/087 Override of traffic control, e.g. by signal transmitted by an emergency vehicle

Abstract

Approaches for prioritizing multiple candidates for preemption of a traffic signal phase at an intersection are disclosed. Light signals transmitted from light-signaling vehicles approaching an intersection encode priority codes using a first set of values. Radio signals from radio-signaling vehicles approaching the intersection encode priority codes using a second set of values. A set of preemption candidates is determined from the light and radio signals, as well as from network-based requests, and a respective relative priority of each preemption candidate based on the priority code of each preemption candidate is determined. A request output for preemption of the traffic signal phase for a preemption candidate having a highest priority.

Claims

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.

2. The method of claim 1, further comprising:

receiving a respective message packet from one or more network-coupled vehicles approaching the intersection, each respective message packet encoding respective location data and encoding a respective priority code using the second set of values, the encoded priority code representing a respective network-packet-based preemption request; and

adding a respective preemption candidate to the set of preemption candidates for each network-packet-based preemption request.

3. The method of claim 1, wherein:

the adding of the preemption candidate to the set of preemption candidates for each light-emitter-based preemption request includes determining for each of the one or more light-signaling vehicles whether or not the light-signaling vehicle is within a range of the intersection based on intensity of the respective light signal, and adding the preemption candidate to the set of preemption candidates in response to the light-signaling vehicle being within the range;

the adding of the preemption candidate to the set of preemption candidates for each radio-transmitter-based preemption request includes determining for each of the one or more radio-signaling vehicles whether or not the radio-signaling vehicle is within the range of the intersection based on the location data, and adding the preemption candidate to the set of preemption candidates in response to the radio-signaling vehicle being within the range.

4. The method of claim 3, further comprising:

receiving a respective message packet from one or more network-coupled vehicles approaching the intersection, each respective message packet encoding respective location data and encoding a respective priority code using the second set of values, the encoded priority code representing a respective network-packet-based preemption request; and

determining for each of the one or more network-coupled vehicles whether or not the network-connected vehicle is within the range of the intersection based on the location data; and

adding a respective preemption candidate to the set of preemption candidates for each network-packet-based preemption request.

5. The method of claim 3, further comprising:

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

in response to the in-progress preemption candidate being for a light-signaling vehicle and further in response to determining that the light-signaling vehicle is not in range of the intersection, activating a timer and maintaining the preemption request in favor of the in-progress preemption candidate;

in response to the in-progress preemption candidate being from a radio-signaling vehicle and further in response to determining that the radio-signaling vehicle is not in range of the intersection, activating a timer and maintaining the preemption request in favor of the in-progress preemption candidate;

in response to expiration of the timer, terminating the in-progress preemption candidate.

6. The method of claim 5, further comprising:

receiving a respective message packet from one or more network-coupled vehicles approaching the intersection, each respective message packet encoding respective location data and encoding a respective priority code using the second set of values, the encoded priority code representing a respective network-packet-based preemption request; and

in response to the in-progress preemption candidate being from a network-coupled vehicle and further in response to determining that the message packet-signaling vehicle is not in range of the intersection, activating a timer and maintaining the preemption request in favor of the in-progress preemption candidate.

7. The method of claim 5, further comprising:

wherein each preemption candidate is associated with an approach to the intersection for which a green phase of the traffic signal is requested; and

in response to expiration of the timer and the in-progress preemption candidate and a second preemption candidate being associated with the same approach and the in-progress preemption candidate and the second preemption candidate having equivalent priorities, outputting a request for preemption of the traffic signal for the second preemption candidate.

8. The method of claim 1, further comprising:

wherein the preemption candidate is in progress in response to the outputting of the request for preemption; and

in response to a first preemption candidate being in progress and a second preemption candidate in the set having a higher priority than the first preemption candidate, terminating the first preemption candidate and outputting a request for preemption of the traffic signal for the second preemption candidate.

9. The method of claim 1, further comprising:

receiving a respective message packet from one or more network-coupled vehicles approaching the intersection, each respective message packet encoding respective location data and encoding a respective priority code using the second set of values, the encoded priority code representing a respective network-packet-based preemption request;

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

wherein the preemption candidate is in progress in response to the outputting of the request for preemption; and

in response to a first preemption candidate being in progress and a second preemption candidate in the set having a higher priority than the first preemption candidate, terminating the first preemption candidate and outputting a request for preemption of the traffic signal for the second preemption candidate.

10. The method of claim 1, further comprising:

wherein the preemption candidate is in progress in response to the outputting of the request for preemption; and

in response to a first preemption candidate being in progress and two or more preemption candidates in the set having higher priorities than the first preemption candidate, terminating the first preemption candidate, selecting an oldest one of the two or more preemption candidates, and outputting a request for preemption of the traffic signal for the oldest one of the preemption candidates.

11. The method of claim 1, further comprising:

receiving a respective message packet from one or more network-coupled vehicles approaching the intersection, each respective message packet encoding respective location data and encoding a respective priority code using the second set of values, the encoded priority code representing a respective network-packet-based preemption request;

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

wherein the preemption candidate is in progress in response to the outputting of the request for preemption; and

in response to a first preemption candidate being in progress and two or more preemption candidates in the set having higher priorities than the first preemption candidate, terminating the first preemption candidate, selecting an oldest one of the two or more preemption candidates, and outputting a request for preemption of the traffic signal for the oldest one of the preemption candidates.

12. The method of claim 1, wherein the first set of values is different from the second set of values.

13. A traffic signal preemption control system, comprising:

photo-detector circuitry for 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;

a radio signal receiver for 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;

a processor coupled to the photo-detector circuitry and to the radio signal receiver; and

a memory coupled to the processor, wherein the memory is configured with instructions for programming the processor to perform the operations including;

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.

14. The system of claim 13, further comprising:

a network interface coupled to the processor, the network interface configured to receive a respective message packet from one or more network-coupled vehicles approaching the intersection, each respective message packet encoding respective location data and encoding a respective priority code using the second set of values, the encoded priority code representing a respective network-packet-based preemption request; and

wherein the memory is further configured with instructions for programming the processor to perform the operation of adding a respective preemption candidate to the set of preemption candidates for each network-packet-based preemption request.

15. The system of claim 14, wherein:

the adding of the preemption candidate to the set of preemption candidates for each light-emitter-based preemption request includes determining for each of the one or more light-signaling vehicles whether or not the light-signaling vehicle is within a range of the intersection based on intensity of the respective light signal, and adding the preemption candidate to the set of preemption candidates in response to the light-signaling vehicle being within the range;

the adding of the preemption candidate to the set of preemption candidates for each radio-transmitter-based preemption request includes determining for each of the one or more radio-signaling vehicles whether or not the radio-signaling vehicle is within the range of the intersection based on the location data, and adding the preemption candidate to the set of preemption candidates in response to the radio-signaling vehicle being within the range; and

the adding of the respective preemption candidate to the set of preemption candidates for each network-packet-based preemption request includes determining for each of the one or more network-coupled vehicles whether or not the network connected vehicle is within the range of the intersection based on the location data, and adding the preemption candidate to the set of preemption candidates in response to the network-coupled vehicle being within the range.

16. The system of claim 14, further comprising:

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

wherein the memory is further configured with instructions for programming the processor to perform the operations including;

in response to the in-progress preemption candidate being for a light-signaling vehicle and further in response to determining that the light-signaling vehicle is not in range of the intersection, activating a timer and maintaining the preemption request in favor of the in-progress preemption candidate;

in response to the in-progress preemption candidate being from a radio-signaling vehicle and further in response to determining that the radio-signaling vehicle is not in range of the intersection, activating a timer and maintaining the preemption request in favor of the in-progress preemption candidate;

in response to the in-progress preemption candidate being from a network-coupled vehicle and further in response to determining that the message packet-signaling vehicle is not in range of the intersection, activating a timer and maintaining the preemption request in favor of the in-progress preemption candidate; and

in response to expiration of the timer, terminating the in-progress preemption candidate.

17. The system of claim 13, further comprising:

wherein each preemption candidate is associated with an approach to the intersection for which a green phase of the traffic signal is requested; and

the memory is further configured with instructions for programming the processor to perform the operation of outputting, in response to expiration of the timer and the in-progress preemption candidate and a second preemption candidate being associated with the same approach and the in-progress preemption candidate and the second preemption candidate having equivalent priorities, a request for preemption of the traffic signal for the second preemption candidate.

18. The system of claim 13, further comprising:

wherein the preemption candidate is in progress in response to the outputting of the request for preemption;

wherein the adding of the respective preemption candidate to the set of preemption candidates for each light-emitter-based preemption request and the adding of the respective preemption candidate to the set of preemption candidates for each radio-transmitter-based preemption request is repeated for newly received light and radio signals; and

the memory is further configured with instructions for programming the processor to perform the operation of terminating, in response to a first preemption candidate being in progress and a second preemption candidate in the set having a higher priority than the first preemption candidate, the first preemption candidate and outputting a request for preemption of the traffic signal for the second preemption candidate.

19. The system of claim 13, further comprising:

wherein the preemption candidate is in progress in response to the outputting of the request for preemption;

wherein the adding of the respective preemption candidate to the set of preemption candidates for each light-emitter-based preemption request and the adding of the respective preemption candidate to the set of preemption candidates for each radio-transmitter-based preemption request is repeated for newly received light and radio signals; and

the memory is further configured with instructions for programming the processor to perform the operation of terminating, in response to a first preemption candidate being in progress and two or more preemption candidates in the set having higher priorities than the first preemption candidate, the first preemption candidate, selecting an oldest one of the two or more preemption candidates, and outputting a request for preemption of the traffic signal for the oldest one of the preemption candidates.