Adaptive control systems and methods

• US 8,050,854 B1
• Filed: 09/24/2008
• Issued: 11/01/2011
• Est. Priority Date: 11/26/2007
• Status: Active Grant

• Current Assignee: Rhythm Engineering
• Original Assignee: Rhythm Engineering
• Inventors: Penrod, Stephen S., Parker, Arthur S., Bley, James W., Chandra, Reggie J.
• Primary Examiner(s): Elchanti; Hussein A.
• Application Number:
  US12/236,701
• Time in Patent Office: 1,133 Days
• Field of Search: 701117-119, 340917-918
• US Class Current: 701/117
• CPC Class Codes: G08G 1/07 Controlling traffic signals
• CPC Class Codes: G08G 1/081 Plural intersections under common control

Abstract

An adaptive control system controls a traffic signal at a critical intersection that has a most conflicting volume of traffic among volumes of traffic at intersections in a traffic network. The adaptive control system determines a plan identifying a guaranteed green light time and a minimum green duration and a period for the plan. The adaptive control system determines, based on the plan, a non-linear schedule with one or more states corresponding to one or more individual phases with each state having a state start time and a state duration. Queues for individual traffic movements at the critical intersection also may be used to determine the non-linear schedule. The adaptive control system controls the traffic signal according to the non-linear schedule. The adaptive control system transmits its plan to one or more other adaptive control systems for other intersections. The other adaptive control systems determine other plans based on the plan from the adaptive control system and an expected travel time between the critical intersection and the corresponding intersection.

Claims

1. A method for controlling traffic movements for a plurality of traffic intersections each having a volume of traffic comprising:

determining a critical intersection having a most conflicting volume from among the volumes;

determining a plan at an adaptive control system with at least one guaranteed green time and at least one minimum green duration for at least one direction of traffic movement at the critical intersection and a period for the plan;

determining other plans with other guaranteed green times and other minimum green durations for other intersections based on the at least one guaranteed green time and the at least one minimum green duration at the critical intersection and an expected travel time between the critical intersection and the other intersections, each other plan having another period;

determining at least one non-linear schedule for the critical intersection at the adaptive control system based on the at least one guaranteed green time, the at least one minimum green duration, the period, and queue lengths for individual phases at the critical intersection;

determining other non-linear schedules for the other intersections based on the other guaranteed green times, the other minimum green durations, the other periods, and other queue lengths for other individual phases at the other intersections;

controlling at least one traffic signal at the critical intersection according to the at least one non-linear schedule; and

controlling other traffic signals at the other intersections according to the other non-linear schedules.

2. The method of claim 1 wherein:

determining the at least one non-linear schedule at the adaptive control system comprises determining the at least one non-linear schedule at an external adaptive control system; and

controlling the at least one traffic signal according to the at least one non-linear schedule comprises controlling at least one traffic signal controller assembly in a fully actuated mode at the critical intersection by the external adaptive control system according to the at least one non-linear schedule.

3. The method of claim 1 wherein:

determining the at least one non-linear schedule at the adaptive control system comprises determining the at least one non-linear schedule at an integrated adaptive control system; and

controlling the at least one traffic signal according to the at least one non-linear schedule comprises transmitting control signals to the traffic signal from the integrated adaptive control system to control indicators of the traffic signal.

4. The method of claim 1 wherein:

determining the other non-linear schedules comprises determining the other non-linear schedules at external adaptive control systems; and

controlling the other traffic signals according to the other non-linear schedules comprises controlling traffic signal controller assemblies at the other intersections by the external adaptive control systems according to the other non-linear schedules.

5. The method of claim 1 wherein:

determining the other non-linear schedules comprises determining the other non-linear schedules at integrated adaptive control systems; and

controlling the other traffic signals according to the other non-linear schedules comprises transmitting control signals to the other traffic signals from the integrated adaptive control systems to control indicators of the other traffic signal.

6. The method of claim 1 wherein the adaptive control system comprises historical data comprising prior light states generated at the at least one traffic signal for particular individual phases for a configured time frame, and wherein the adaptive control system is configured to receive detector data and to process the detector data to determine the queue lengths, and the method further comprises:

determining when at least some detector data is not received at the adaptive control system; and

determining the at least one non-linear schedule at the adaptive control system based on the plan, and at least some of the historical data, the at least some historical data used in place of at least some queue lengths for the not received detector data.

7. The method of claim 1 wherein the adaptive control system is configured to receive detector data and to process the detector data to determine the queue lengths, the method further comprising:

storing a plurality of light states generated at the traffic signal for particular individual phases for a configured time frame in memory at the adaptive control system; and

when at least some of the detector data is not received at the external adaptive control system, processing at least some of the historical data in place of at least some of the detector data in an emergency mode to determine the non-linear schedule.

8. The method of claim 1 wherein determining the plan comprises:

determining a number of vehicles per second passing through the critical intersection in the at least one direction of traffic movement during a prior period;

multiplying the number of vehicles per second by the prior period to determine an expected number of vehicles to pass through the critical intersection in the selected direction during the plan; and

multiplying a clearance time by the expected number of vehicles to determine the minimum green duration for the plan.

9. The method of claim 1 wherein determining the plan comprises determining the guaranteed green time to be a starting time of the plan.

10. The method of claim 1 wherein determining the plan comprises:

determining a number of vehicles per second passing through the critical intersection in the at least one direction of traffic movement during a time frame the at least one direction of traffic movement has a right-of-way in a prior period;

multiplying the number of vehicles per second by the prior period to determine an expected number of vehicles to pass through the critical intersection in the selected direction during the plan; and

multiplying a clearance time by the expected number of vehicles to determine the minimum green duration for the plan.

11. The method of claim 1 wherein determining the period comprises:

reducing the period from a prior period by a first selected time amount when a non-selected direction of traffic movement at the critical intersection has more than enough time during the prior period to clear traffic for at least one corresponding individual phase in the non-selected direction; and

increasing the period from the prior period by a second selected time amount when the non-selected direction of traffic movement at the critical intersection does not have than enough time during the prior period to clear the traffic for the at least one corresponding individual phase in the non-selected direction.

12. The method of claim 1 wherein determining the period comprises:

reducing the period from a prior period by a first selected time amount when the selected direction of traffic movement at the critical intersection has more than enough time during the prior period to clear traffic for at least one corresponding individual phase in the selected direction; and

increasing the period from the prior period by a second selected time amount when the selected direction of traffic movement at the critical intersection does not have than enough time during the prior period to clear the traffic for the at least one corresponding individual phase in the selected direction.

13. The method of claim 1 wherein:

determining the plan further comprises determining at least one second guaranteed green time and at least one second minimum green duration for a coordinated direction of traffic movement at the critical intersection; and

determining the at least one non-linear schedule for the critical intersection at the adaptive control system comprises determining the at least one non-linear schedule based on the queue lengths and the plan with the at least one guaranteed green time, the at least one green duration, the at least one second guaranteed green time, the at least one second minimum green duration, and the period for the plan.

14. The method of claim 1 wherein:

determining the other plans further comprises determining, for each corresponding other plan, a corresponding other guaranteed green time, a corresponding other green duration, at least one second corresponding guaranteed green time, and at least one second corresponding minimum green duration for a coordinated direction of traffic movement at a corresponding intersection, each corresponding other plan having a corresponding other period; and

determining the other non-linear schedules for the other intersections at the other adaptive control system comprises, for each other non-linear schedule, determining the other non-linear schedule based on corresponding queue lengths at the corresponding intersection and the corresponding other plan.

15. The method of claim 1 further comprising:

receiving progression data at the adaptive control system for at least one progression, the progression data comprising at least one number of vehicles approaching the critical intersection and at least one progression time for the at least one number of vehicles approaching the critical intersection; and

determining the at least one non-linear schedule at the adaptive control system based on the plan, the queue lengths, and the progression data.

16. The method of claim 1 further comprising transmitting the plan from the at least one adaptive control system to the other adaptive control systems.

17. The method of claim 1 further comprising:

determining the non-linear schedule by determining first states, first state start times, and first state durations for a main direction;

determining second states, second state start times, and second state durations for a cross street direction; and

ordering the first states and second states in a variable order.

18. The method of claim 1 further comprising determining the non-linear schedule by:

establishing a start time for the non-linear schedule and an end time for the non-linear schedule;

determining a first partial schedule by marking time occupied by coordinated phases as committed;

for each individual phase with an unaccounted queue, determine a plurality of potential schedules from the first partial schedule by fitting the unaccounted individual phase into areas where no non-compatible phase already exists;

applying a scoring function to each potential schedule, the scoring function comprising multiplying each queue length for each unaccounted individual phase by a waiting time for the unaccounted individual phase and summing each multiplied queue length and waiting time to obtain a score for each potential schedule;

selecting the potential schedule with a lowest score as the non-linear schedule;

filling at least one empty area in the schedule with at least one compatible individual phase; and

generating the non-linear schedule from the potential schedule with the lowest score and the at least one compatible individual phase.

19. The method of claim 1 further comprising:

determining a plurality of potential solutions for a main direction and a cross street direction for the non-linear schedule based on the queue lengths at the critical intersection, each potential solution having transition times and waiting times for a plurality of potential state sequences;

selecting a solution for each direction having a lowest waiting time and a shortest transition time; and

generating the non-linear schedule with the selected main street solution and the selected cross street solution.

20. A method for controlling traffic movements for a plurality of traffic intersections each having a volume of traffic comprising:

determining a critical intersection having a most conflicting volume from among the volumes;

determining at least one guaranteed green time and at least one minimum green duration for at least one direction of traffic movement at the critical intersection and a period between at least one guaranteed green time at the critical intersection and a next guaranteed green time for the at least one direction of traffic movement at the critical intersection;

determining at least one other guaranteed green time and at least one other minimum green duration for at least one other intersection based on the at least one guaranteed green time and the at least one minimum green duration at the critical intersection and an expected travel time between the critical intersection and the at least one other intersection;

determining at least one non-linear schedule for the critical intersection based on the at least one guaranteed green time, the at least one minimum green duration, the period, and queue lengths for individual phases at the critical intersection;

determining at least one other non-linear schedule for the at least one other intersection based on the at least one other guaranteed green time, the at least one other minimum green duration, and other queue lengths at the at least one other intersection;

controlling at least one traffic signal at the critical intersection according to the at least one non-linear schedule; and

controlling at least one other traffic signal at the at least one other intersection according to the at least one other non-linear schedule.

21. The method of claim 20 wherein:

determining the at least one non-linear schedule comprises determining the at least one non-linear schedule at an external adaptive control system; and

controlling the at least one traffic signal according to the at least one non-linear schedule comprises controlling at least one traffic signal controller assembly at the critical intersection by the external adaptive control system according to the at least one non-linear schedule.

22. The method of claim 20 wherein:

determining the at least one non-linear schedule comprises determining the at least one non-linear schedule at an integrated adaptive control system; and

controlling the at least one traffic signal according to the at least one non-linear schedule comprises transmitting control signals from the integrated adaptive control system to the traffic signal to control indicators of the traffic signal.

23. The method of claim 20 wherein:

determining the at least one other non-linear schedule comprises determining the at least one other non-linear schedule at least one other external adaptive control system; and

controlling the at least one other traffic signal according to the at least one other non-linear schedule comprises controlling at least one other traffic signal controller assembly at the at least one other intersection by the at least one other external adaptive control system according to the at least one other non-linear schedule.

24. The method of claim 20 wherein:

determining the at least one other non-linear schedule comprises determining the at least one other non-linear schedule at least one other integrated adaptive control system; and

controlling the at least one other traffic signal according to the at least one other non-linear schedule comprises transmitting control signals to the at least one other traffic signal from the at least one integrated adaptive control system to control indicators of the at least one other traffic signal.

25. The method of claim 20 further comprising:

determining the at least one non-linear schedule at an adaptive control system comprising prior light states generated at the at least one traffic signal for particular individual phases for a configured time frame, wherein the adaptive control system is configured to receive detector data and to process the detector data to determine the queue lengths;

determining when at least some detector data is not received at the adaptive control system; and

determining the at least one non-linear schedule at the adaptive control system based on the plan, and at least some of the historical data, the at least some historical data used in place of at least some queue lengths for the not received detector data.

26. The method of claim 20 further comprising:

determining the at least one non-linear schedule at an adaptive control system configured to receive detector data and to process the detector data to determine the queue lengths;

storing a plurality of light states generated at the traffic signal for particular individual phases for a configured time frame in memory at the adaptive control system; and

when at least some of the detector data is not received at the external adaptive control system, processing at least some of the historical data in place of at least some of the detector data in an emergency mode to determine the non-linear schedule.

27. A method for controlling traffic movements for a plurality of traffic intersections each having a volume of traffic comprising:

determining a critical intersection having a most conflicting volume from among the volumes;

determining at least one guaranteed green time and at least one minimum green duration for at least one direction of traffic movement at the critical intersection;

determining other guaranteed green times and other minimum green durations for other intersections based on the at least one guaranteed green time and the at least one minimum green duration at the critical intersection and an expected travel time between the critical intersection and the other intersections;

determining at least one non-linear schedule for the critical intersection based at least on the at least one guaranteed green time and the at least one minimum green duration;

determining other non-linear schedules for the other intersections based on the other guaranteed green times and other minimum green durations;

controlling at least one traffic signal at the critical intersection according to the at least one non-linear schedule; and

controlling other traffic signals at the other intersections according to the other non-linear schedules.

28. The method of claim 27 wherein:

controlling the at least one signal at the critical intersection comprises controlling at least one traffic signal controller assembly at the critical intersection by at least one external adaptive control system according to the at least one non-linear schedule.

29. The method of claim 27 wherein:

controlling other traffic signals at other intersections comprises controlling other traffic signal controller assemblies at the other intersections by other external adaptive control systems according to the other non-linear schedules.

30. The method of claim 27 further comprising:

determining the at least one non-linear schedule at an adaptive control system comprising prior light states generated at the at least one traffic signal for particular individual phases for a configured time frame, wherein the adaptive control system is configured to receive detector data and to process the detector data to determine the queue lengths;

determining when at least some detector data is not received at the adaptive control system; and

determining the at least one non-linear schedule at the adaptive control system based on the plan, and at least some of the historical data, the at least some historical data used in place of at least some queue lengths for the not received detector data.

31. The method of claim 27 further comprising:

determining the at least one non-linear schedule at an adaptive control system configured to receive detector data and to process the detector data to determine the queue lengths;

storing a plurality of light states generated at the traffic signal for particular individual phases for a configured time frame in memory at the adaptive control system; and

when at least some of the detector data is not received at the external adaptive control system, processing at least some of the historical data in place of at least some of the detector data in an emergency mode to determine the non-linear schedule.

32. A system for controlling traffic movements for a plurality of traffic intersections each having a volume of traffic, the system comprising:

an adaptive control system at a critical intersection having a most conflicting volume from among the volumes and configured to;

determine a plan with at least one guaranteed green time and at least one minimum green duration for at least one direction of traffic movement at the critical intersection and a period for the plan;

determine at least one non-linear schedule for the critical intersection based on the at least one guaranteed green time, the at least one minimum green duration, the period, and queue lengths for individual phases at the critical intersection; and

control at least one traffic signal at the critical intersection according to the at least one non-linear schedule; and

a plurality of other adaptive control systems, each other adaptive control system configured to;

determine a corresponding plan, each corresponding plan comprising a corresponding guaranteed green time and a corresponding minimum green duration for a corresponding intersection based on the at least one guaranteed green time and the at least one minimum green duration at the critical intersection and an expected travel time between the critical intersection and the corresponding intersection, each corresponding plan having a corresponding period;

determine a corresponding non-linear schedule for the corresponding intersection based on the corresponding plan and corresponding queue lengths for corresponding individual phases for the corresponding intersection, each corresponding non-linear schedule comprising another plurality of corresponding states having a corresponding state order, each corresponding state having a corresponding state start time and a corresponding state duration; and

control a corresponding traffic signal at the corresponding intersection according to the corresponding non-linear schedule.

33. The system of claim 32 wherein:

the adaptive control system comprises an external adaptive control system; and

the external adaptive control system is configured to control the at least one traffic signal at the critical intersection by controlling at least one traffic signal controller assembly in a fully actuated mode at the critical intersection according to the at least one non-linear schedule.

34. The system of claim 32 wherein:

the adaptive control system comprises an integrated adaptive control system; and

the integrated adaptive control system is configured to determine the at least one non-linear schedule and control the at least one traffic signal at the critical intersection by transmitting control signals to the traffic signal to control indicators of the traffic signal.

35. The system of claim 32 wherein:

each other adaptive control system comprises an external adaptive control system configured to determine the corresponding non-linear schedule; and

each external adaptive control system is configured to control the corresponding traffic signal according to the corresponding non-linear schedule by controlling a corresponding traffic signal controller assembly at the corresponding intersection according to the corresponding non-linear schedule.

36. The system of claim 32 wherein:

each other adaptive control system comprises an external adaptive control system configured to determine the corresponding non-linear schedule; and

each integrated adaptive control system is configured to determine the corresponding non-linear schedule and control the corresponding traffic signal at the corresponding intersection by transmitting control signals to the corresponding traffic signal to control indicators of the corresponding traffic signal.

37. The system of claim 32 wherein:

the adaptive control system comprises historical data comprising prior light states generated at the at least one traffic signal for particular individual phases for a configured time frame; and

the adaptive control system is configured to;

receive detector data and to process the detector data to determine the queue lengths;

determine when at least some detector data is not received at the adaptive control system; and

determine the at least one non-linear schedule at the adaptive control system based on the plan, and at least some of the historical data, the at least some historical data used in place of at least some queue lengths for the not received detector data.

38. The system of claim 32 wherein the adaptive control system is configured to:

receive detector data and to process the detector data to determine the queue lengths;

store a plurality of light states generated at the traffic signal for particular individual phases for a configured time frame in memory at the adaptive control system; and

when at least some of the detector data is not received at the adaptive control system, process at least some of the historical data in place of at least some of the detector data in an emergency mode to determine the non-linear schedule.

39. The system of claim 32 wherein the adaptive control system is configured to determine the plan by:

determining a number of vehicles per second passing through the critical intersection in the at least one direction of traffic movement during a prior period;

multiplying the number of vehicles per second by the prior period to determine an expected number of vehicles to pass through the critical intersection in the selected direction during the plan; and

multiplying a clearance time by the expected number of vehicles to determine the minimum green duration for the plan.

40. The system of claim 32 wherein the adaptive control system is configured to determine the plan by:

determining a number of vehicles per second passing through the critical intersection in the at least one direction of traffic movement during a time frame the at least one direction of traffic movement has a right-of-way in a prior period;

multiplying the number of vehicles per second by the prior period to determine an expected number of vehicles to pass through the critical intersection in the selected direction during the plan; and

multiplying a clearance time by the expected number of vehicles to determine the minimum green duration for the plan.

41. The system of claim 32 wherein the adaptive control system is configured to determine the plan by determining the guaranteed green time to be a starting time of the plan.

42. The system of claim 32 wherein the adaptive control system is configured to determine the period by:

reducing the period from a prior period by a first selected time amount when a non-selected direction of traffic movement at the critical intersection has more than enough time during the prior period to clear traffic for at least one corresponding individual phase in the non-selected direction; and

increasing the period from the prior period by a second selected time amount when the non-selected direction of traffic movement at the critical intersection does not have than enough time during the prior period to clear the traffic for the at least one corresponding individual phase in the non-selected direction.

43. The system of claim 32 wherein the adaptive control system is configured to determine the period by:

reducing the period from a prior period by a first selected time amount when the selected direction of traffic movement at the critical intersection has more than enough time during the prior period to clear traffic for at least one corresponding individual phase in the selected direction; and

increasing the period from the prior period by a second selected time amount when the selected direction of traffic movement at the critical intersection does not have than enough time during the prior period to clear the traffic for the at least one corresponding individual phase in the selected direction.

44. The system of claim 32 wherein the adaptive control system is configured to determine the non-linear schedule by determining first states, first state start times, and first state durations for a main direction, determining second states, second state start times, and second state durations for a cross street direction, and ordering the first states and second states in the variable order.

45. The system of claim 32 wherein the adaptive control system is configured to determine the non-linear schedule by:

establishing a start time for the non-linear schedule and an end time for the non-linear schedule;

determining a first partial schedule by marking time occupied by coordinated phases as committed;

for each individual phase with an unaccounted queue, determine a plurality of potential schedules from the first partial schedule by fitting the unaccounted individual phase into areas where no non-compatible phase already exists;

applying a scoring function to each potential schedule, the scoring function comprising multiplying each queue length for each unaccounted individual phase by a waiting time for the unaccounted individual phase and summing each multiplied queue length and waiting time to obtain a score for each potential schedule;

selecting the potential schedule with a lowest score as the non-linear schedule;

filling at least one empty area in the schedule with at least one compatible individual phase; and

generating the non-linear schedule from the potential schedule with the lowest score and the at least one compatible individual phase.

46. The system of claim 32 wherein the adaptive control system is configured to determine a plurality of potential solutions for a main direction and a cross street direction based on the queue lengths, each potential solution having transition times and waiting times for a plurality of potential state sequences, to select a solution for each direction having a lowest waiting time and a shortest transition time, and to generate the non-linear schedule with the selected main street solution and the selected cross street solution.

47. The system of claim 32 wherein the adaptive control system is configured to:

determine the plan by determining at least one second guaranteed green time and at least one second minimum green duration for a coordinated direction of traffic movement at the critical intersection; and

determine the at least one non-linear schedule for the critical intersection at the adaptive control system by determining the at least one non-linear schedule based on the queue lengths and the plan with the at least one guaranteed green time, the at least one green duration, the at least one second guaranteed green time, the at least one second minimum green duration, and the period for the plan.

48. The system of claim 32 wherein the adaptive control system is configured to:

determine the other plans by determining, for each corresponding other plan, a corresponding other guaranteed green time, a corresponding other green duration, at least one second corresponding guaranteed green time, and at least one second corresponding minimum green duration for a coordinated direction of traffic movement at a corresponding intersection, each corresponding other plan having a corresponding other period; and

determine the other non-linear schedules for the other intersections by determining, for each other non-linear schedule, the other non-linear schedule based on corresponding queue lengths at the corresponding intersection and the corresponding other plan.

49. A system for controlling traffic movements for a plurality of traffic intersections each having a volume of traffic, the system comprising:

an adaptive control system configured to;

determine a critical intersection having a most conflicting volume from among the volumes;

determine a plan with at least one guaranteed green time and at least one minimum green duration for at least one direction of traffic movement at the critical intersection and a period for the plan;

determine at least one non-linear schedule for the critical intersection based on the at least one guaranteed green time, the at least one minimum green duration, the period, and queue lengths for individual phases at the critical intersection; and

control at least one traffic signal at the critical intersection according to the at least one non-linear schedule; and

at least one other adaptive control system configured to;

determine at least one other guaranteed green time and at least one other minimum green duration for at least one other intersection based on the at least one guaranteed green time and the at least one minimum green duration at the critical intersection and an expected travel time between the critical intersection and the at least one other intersection;

determine at least one other non-linear schedule for the at least one other intersection based on the at least one other guaranteed green time, the at least one other minimum green duration, and other queue lengths at the at least one other intersection; and

control at least one other traffic signal at the at least one other intersection according to the at least one other non-linear schedule.

50. The system of claim 49 wherein:

the adaptive control system comprises an external adaptive control system; and

the external adaptive control system is configured to control the at least one traffic signal at the critical intersection by controlling at least one traffic signal controller assembly at the critical intersection according to the at least one non-linear schedule.

51. The system of claim 49 wherein:

the adaptive control system comprises an integrated adaptive control system; and

the integrated adaptive control system is configured to determine the at least one non-linear schedule and control the at least one traffic signal at the critical intersection by transmitting control signals to the traffic signal to control indicators of the traffic signal.

52. The system of claim 49 wherein:

the at least one other adaptive control system comprises at least one external adaptive control system configured to determine the at least one other non-linear schedule; and

the at least one external adaptive control system is configured to control the at least one other traffic signal according to the at least one other non-linear schedule by controlling at least one other traffic signal controller assembly at the at least one other intersection according to the at least one other non-linear schedule.

53. The system of claim 49 wherein:

the at least one other adaptive control system comprises at least one integrated adaptive control system configured to determine the at least one other non-linear schedule; and

the at least one integrated adaptive control system is configured to determine the at least one other non-linear schedule and control the at least one other traffic signal at the at least one other intersection by transmitting control signals to the at least one other traffic signal to control indicators of the at least one other traffic signal.

54. The system of claim 49 wherein:

the adaptive control system comprises prior light states generated at the at least one traffic signal for particular individual phases for a configured time frame; and

the adaptive control system is configured to;

receive detector data and to process the detector data to determine the queue lengths;

determine when at least some detector data is not received at the adaptive control system; and

determine the at least one non-linear schedule at the adaptive control system based on the plan, and at least some of the historical data, the at least some historical data used in place of at least some queue lengths for the not received detector data.

55. The system of claim 49 wherein the adaptive control system is configured to:

receive detector data and to process the detector data to determine the queue lengths;

store a plurality of light states generated at the traffic signal for particular individual phases for a configured time frame in memory at the adaptive control system; and

when at least some of the detector data is not received at the external adaptive control system, process at least some of the historical data in place of at least some of the detector data in an emergency mode to determine the non-linear schedule.

56. A system for controlling traffic movements for a plurality of traffic intersections each having a volume of traffic, the system comprising:

an adaptive control system at a critical intersection having a most conflicting volume from among the volumes and configured to;

determine at least one guaranteed green time and at least one minimum green duration for at least one direction of traffic movement at the critical intersection;

determine at least one non-linear schedule for the critical intersection based at least on the at least one guaranteed green time and the at least one minimum green duration; and

control at least one traffic signal at the critical intersection according to the at least one non-linear schedule; and

a plurality of other adaptive control systems, each configured to;

determine another guaranteed green time and other minimum green duration for another intersection based on the at least one guaranteed green time and the at least one minimum green duration at the critical intersection and an expected travel time between the critical intersection and the other intersection;

determine another non-linear schedule for the other intersection based on the other guaranteed green time and other minimum green duration; and

control another traffic signal at the other intersection according to the other non-linear schedule.

57. The system of claim 56 wherein:

the adaptive control system comprises an external adaptive control system; and

the external adaptive control system is configured to control the at least one traffic signal at the critical intersection by controlling at least one traffic signal controller assembly at the critical intersection according to the at least one non-linear schedule.

58. The system of claim 56 wherein:

each other adaptive control system comprises an external adaptive control system; and

each external adaptive control system is configured to control the other traffic signal according to the other non-linear schedule by controlling a corresponding traffic signal controller assembly at the other intersection according to the other non-linear schedule.

59. The system of claim 56 wherein:

the adaptive control system comprises prior light states generated at the at least one traffic signal for particular individual phases for a configured time frame; and

the adaptive control system is configured to;

receive detector data and to process the detector data to determine the queue lengths;

determine when at least some detector data is not received at the adaptive control system; and

determine the at least one non-linear schedule at the adaptive control system based on the plan, and at least some of the historical data, the at least some historical data used in place of at least some queue lengths for the not received detector data.

60. The system of claim 56 wherein the adaptive control system is configured to:

receive detector data and to process the detector data to determine the queue lengths;

store a plurality of light states generated at the traffic signal for particular individual phases for a configured time frame in memory at the adaptive control system; and

when at least some of the detector data is not received at the external adaptive control system, process at least some of the historical data in place of at least some of the detector data in an emergency mode to determine the non-linear schedule.