Highway traffic signal local controller
First Claim
1. A signal indication switching method for use in controlling traffic signal indicators for control of traffic movements at an intersection, which method includes linear programming solutions for maximum, optimum and minimum cycle lengths and maximum, optimum and minimum phase times, said method comprising;
- generating a movement-phase matrix, M, having data elements for defining the relationship between movements and phases where Mij =1 indicates that movement i is included in phase j, and Mij =0 indicates that movement i is not included in phase j, wherein each of said movements identifies a green display of said traffic signal indicators for a single traffic movement at said intersection and each of said phases identifies a green display of said traffic signal indicators given to a combination of traffic movements at said intersection,constructing linear constraints using data elements from the movement-phase matrix, M, incoming and saturation flow rates, and lost time constants for each movement to be implemented during the next cycle of traffic movements,computing said maximum, optimum and minimum cycle lengths and maximum, optimum and minimum phase times using the said linear constraints in linear programming solutions thereof,using said computed maximum, optimum and minimum phase times for determining maximum, optimum and minimum movement green times for movements to be implemented, andusing the maximum, optimum and minimum green times and said maximum, optimum and minimum cycle lengths, to obtain signal timing parameters for control of said signal indicators at the intersection.
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Accused Products
Abstract
A highway traffic control method is shown in which the control method (80) and phasing scheme (82) are defined and recall switches are set (84) every cycle of operation. In time-of-day control methods (FIGS. 14 and 15) timing parameters (86) also are defined every cycle, and common cycle length and planned offset are computed (90) at the local master controller (16). Offset deviation is measured (94) and used along with the computed cycle length for adjustment of the local signal timing (96). Following execution of signal control, the control method, phasing scheme and timing parameters are defined and recall switches set in preparation for the next cycle of operation. In the traffic-responsive method, traffic data from local detectors are obtained and processed (100) and, using this data, signal timing parameters are computed using linear programming (102). In the traffic-adaptive method (FIG. 20 ) real-time detector information is processed (226) and used for further adjustment of signal timing parameters (228). Inputs for the linear programming solution (114) include incoming and saturation flow rates (110) and data from a movement-phase matrix M (126) which defines the relationship between movements and phases. Matrix M is generated using data from a green-green conflict matrix G (128) which identifies conflicting traffic movement. Linear program constraints for less preferred movements (118) are made equalities to reduce the number of multiple solutions. Linear programming is used to obtain maximum, optimum, and minimum cycle lengths and green times. Provision is made for adjustment of linear program solutions if the solution is not acceptable (178, 192 and 206). If the linear program has no solution (172, 188 and 202) maximum, optimum and minimum cycle lengths and green times from time-of-day tables are used.
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Citations
38 Claims
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1. A signal indication switching method for use in controlling traffic signal indicators for control of traffic movements at an intersection, which method includes linear programming solutions for maximum, optimum and minimum cycle lengths and maximum, optimum and minimum phase times, said method comprising;
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generating a movement-phase matrix, M, having data elements for defining the relationship between movements and phases where Mij =1 indicates that movement i is included in phase j, and Mij =0 indicates that movement i is not included in phase j, wherein each of said movements identifies a green display of said traffic signal indicators for a single traffic movement at said intersection and each of said phases identifies a green display of said traffic signal indicators given to a combination of traffic movements at said intersection, constructing linear constraints using data elements from the movement-phase matrix, M, incoming and saturation flow rates, and lost time constants for each movement to be implemented during the next cycle of traffic movements, computing said maximum, optimum and minimum cycle lengths and maximum, optimum and minimum phase times using the said linear constraints in linear programming solutions thereof, using said computed maximum, optimum and minimum phase times for determining maximum, optimum and minimum movement green times for movements to be implemented, and using the maximum, optimum and minimum green times and said maximum, optimum and minimum cycle lengths, to obtain signal timing parameters for control of said signal indicators at the intersection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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23. A method as defined in claim 1 wherein the step of obtaining signal timing parameters includes,
adjusting the maximum, optimum and minimum green times and maximum, optimum and minimum cycle lengths for coordinating control of traffic at the intersection with traffic at other intersections within a group of intersections. -
24. A method as defined in claim 1 which includes adjusting said saturation flow rates by a weather coefficient for reducing said saturation flow rates during inclement weather condition.
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25. A method as defined in claim 1 wherein the step of generating a movement-phase matrix, M, includes using data elements from a green-green conflict matrix, G, which indicate conflicting pairs of traffic movements.
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26. A method as defined in claim 1 wherein the step of obtaining signal timing parameters for control of signal indicators includes adjusting said optimum green times and said optimum cycle length within limits of said maximum and minimum green times and maximum and minimum cycle lengths to accommodate a common cycle length and to catch up with a planned offset.
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27. A method as defined in claim 26 which further includes adjusting said signal timing parameters within said limits in response to real-time detector information.
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28. A signal indication switching method for use in controlling traffic signal indicators for control of traffic movement at an intersection, which method includes the following machine-implemented, non-metal, steps,
defining the signal status for each movement by a signal status vector, At, which indicates the remaining green plus intergreen times for green movements, when one or more remaining green plus intergreen times becomes less than a predetermined value, δ -
t, creating a zero-one lose vector, S1, in which a data element of 1 indicates that the movement will lose green,
creating a zero-one gain vector, Sg, in which a data element of 1 indicates the movement to gain green, creating a zero-one remain vector, Sr, in which a data element of 1 identifies the movement(s) that will keep the green, determining whether or not the movement identified by the gain vector, Sg, should be skipped, if the movement identified by the gain vector, Sg, should not be skipped, then determining whether or not the new movement identified by the gain vector, Sg, will conflict with the remaining green movement(s), if the movement identified by the gain vector, Sg, does not conflict with said remaining green movement(s), then defining new green times for use in the new movement, and employing said new green times in controlling said traffic signal indicators. - View Dependent Claims (29, 30, 31, 32, 33)
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t, creating a zero-one lose vector, S1, in which a data element of 1 indicates that the movement will lose green,
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34. A signal control method for use in a traffic control system which includes a plurality of local controllers for control of traffic signal indicators at a plurality of intersections along an artery within an area and, including a local master controller operatively connected to each of said local controllers, said method comprising
at the local controllers, defining local signal timing parameters including maximum, optimum and minimum cycle lengths and maximum, optimum and minimum green times for each movement to be implemented at the associated intersection, computing at the local master controller a common cycle length using said optimum cycle lengths from said local controllers, computing at the local master controller planned offset times for each of the local controllers, at the local controllers, adjusting said local optimum green times and optimum cycle length within limits of said local maximum and minimum green times and maximum and minimum cycle lengths using the common cycle length and the planned offset times to coordinate operation of said traffic signal indicators at said plurality of intersections.
Specification