title: Physics of traffic gridlock in a city.
abstract: Based on simulations of stochastic three-phase and two-phase traffic flow models, we reveal that at a signalized city intersection under small link inflow rates at which a vehicle queue developed during the red phase of the light signal dissolves fully during the green phase, i.e., no traffic gridlock should be expected, nevertheless, spontaneous traffic breakdown with subsequent city gridlock occurs with some probability after a random time delay. In most cases, this traffic breakdown is initiated by a phase transition from free flow to a synchronized flow occurring upstream of the queue at the light signal. The probability of traffic breakdown at the light signal is an increasing function of the link inflow rate and duration of the red phase of the light signal.
authors.affiliation: Daimler AG, GR/PTF, HPC:G021, D-71059 Sindelfingen, Germany.
authors.forename: Boris S
authors.initials: BS
authors.lastname: Kerner