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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