Queue spillovers in city street networks with signal-controlled intersections

Quick and reliable estimation of traffic conditions is of critical importance for advanced traffic management systems, especially when heavy congestion occurs. This paper proposes a methodology to predict queue spillovers in city street networks with signalized intersections using data from loop detectors (counts and occupancy). The key idea of the developed methodology is that when spillovers from a downstream link, vehicle arrivals from the upstream signal line, queues discharge at rates smaller than the saturation flow. The paper underlines the significant effect of spillovers in congestion and analyzes an extension of the method to capture variations in vehicle lengths. It also shows that a macroscopic diagram connecting spillovers with car density exists for large scale urban networks which are homogeneously congested. The application of the methodology on an arterial site and the comparison with field data shows that it accurately identifies spillovers in city street networks with signal-controlled intersections.