The assignment of traffic signals to stages to be used by optimal control is split up into two sub-problems: finding the set of all the allowed stages and choosing stages to use. Allowed stages are built by considering each signal and the set of its compatible signals. The choice of the stages to use is made in function of the saturation and demand flows by computing the minimum cycle length that avoids saturation and by eliminating stages while this cycle is possible. Validation by comparing performances of the sets of stages chosen by the algorithm to those of other sets of stages, in open and closed loop, shows a delay reduction (6% to 85%). Real time control gives better results than fixed cycle with an optimal set of stages, but gives worst results with other sets. The method could improve fixed plan production and allows the use of a set of stages for which the online optimisation is tractable.
Abstract