In dense, closely spaced networks of arterial streets, queue spillback, or intersection blockage, is a major contributor to recurrent congestion. It has already been established that existing capacity manuals and signal analysis software are deficient in their consideration of downstream effects on movement discharge at signalised intersections. An analytical model is described that estimates capacities and delays for movements subject to blocking. The phenomenon of intersection blockage is modelled by way of a modified effective green period whereby upstream movement discharge occurs at saturation flow rate until the onset of blocking when discharge falls instantaneously to zero. The model is model is capable of considering a wide range of operating conditions including multiple upstream movements, shared lanes at the downstream intersection, and multiple upstream and downstream green periods per cycle with different saturation flow rates. An illustration of the application of the model to a real world paired intersection system is given. (A)
Abstract