DETECTION AND CONTROL OF CONGESTION IN URBAN ROAD NETWORKS
J. Shibata, T. Yamamoto · Traffic engineering & control · 1984
Accurate and rapid detection of congestion conditions has been made possible based on the relationship between speed and queue length. Utilising congestion levels categorised by queue lengths, two new functions have been introduced: (1) congestion control, in which cycle and split patterns for a sub-area are selected based on the relative detected congestion levels of intersecting roads. (2) multi-phase split control, in which the multi-phase split of an isolated intersection is calculated by adding the phase saturation level to the product of the total unused green time and the standard split during non-congestion, and the congestion level is used to control multi-phase split during congestion. These two functions have been confirmed to have advantageous results in actual traffic control systems. (TRRL)