Spatio-Temporal Evolution of Traffic Congestions on Urban Freeways

In this paper, a macroscopic approach Cell Transmission Model (CTM) based on traffic wave theory where traffic flow is treated as a one-dimensional compressible fluid with variable characteristics is applied to describe the spatio-temporal evolution of traffic congestions on urban freeways. The evolution is significant to reflect the formulation, continuance and dissipation of queues. This paper improves CTM that combines both short-term traffic flow data and occupancy data collected by inductive loops when common congestions or incidents occur. A piecewise linear regression model is performed with a validation of real traffic data collected on freeway of Queen Elizabeth-Ontario, Canada, then simulation results of CTM are quantitatively compared with field data, the results show that CTM can provide a relatively high accuracy of spatio-temporal evolution of traffic congestions.