Network-Based Optimization of Traffic Signals Timing Using Internal Metering Policy by Paying Attention to Upstream Intersections

Timing actuated traffic signals is usually done by methodologies considering minimizing delay times, stop times, queue length etc. as the core idea. In none of such methodologies the effects of other adjacent intersections are considered. In other words, there is no control over queue congestion in such methodologies. In the proposed algorithm of traffic signs optimization, using an internal (RT/IMPOST) metering policy maintains an optimum queue length ratio within the network. In this method, the effect of upstream intersection is considered in timing procedure. In this paper a traffic signals optimization method is elaborated and proposed for the whole network and has been particularized in three aspects: ۱) The queue length ratio within the whole network: in this aspect, the queue length ratio has been conserved within an optimum interval ۲) the queue time ratio: the time ratio of vehicles movement in congested condition to the free flow condition has been restricted and ۳) the queue speed ratio: in this case the proportion of vehicles speed in congested condition to free flow speed has been restricted and conserved. The aim of these algorithms is to minimize the difference of queue length, time and speed ratios with their corresponding optimum values which could lead into a more optimized timing and determining efficient green phase timing for each intersection. With comparison of the results taken from each of these three algorithms, it was cleared up that queue length ratio algorithm has better results for oversaturated networks and could ameliorate the traffic conditions better compared to the other algorithms.