Macroscopic phase states of traffic flow in tunnels

The studies of traffic flows are reviewed and different approaches in the analysis of the phase states of flows and the fundamental diagram are described. A comparison with the experimental results is performed. The attention is focused on the analysis of the empirical data collected on the linear branch of the Lefortovo tunnel (Moscow’s third ring road). The analysis performed gives a fundamental diagram with a very complex structure. It is shown that the congested traffic flow observed in the tunnel can be considered indeed as cooperative vehicle motion. In particular, it is established that there are long-scale spatial correlations in the motion speed and that the fundamental diagram contains a region of widely scattered states. These two features are typical of phase cooperative vehicle motion. The phase portrait of the traffic flow dynamics is analyzed. Two regions with radically different properties, separated by a narrow layer with a nearly constant vehicle density, are revealed. One of these regions corresponds to cooperative vehicle motion and contains a core with chaotic dynamics. The other part of the phase plane describes the jammed phase formation.