TRAFFIC DENSITY CONTROL FOR AUTOMATED HIGHWAY SYSTEMS

Traffic flow instabilities such as traffic congestion are often caused by ad hoc and inappropriate speeds and headways that humans choose wh en they operate their vehicles. In an automated highway system (AHS) e nvironment, the driver's actions are replaced by those of a computer c ontrol system that is designed to optimize traffic flow. On the micros copic level, each vehicle is driven by a computer control system, whic h, based on the actions of the surrounding vehicles, sends the appropr iate commands to the throttle/brake/steering actuators. On the macrosc opic level, a roadway controller calculates the desired speed commands to be followed by vehicles in each section of the freeway lanes in or der to achieve desired traffic density distributions that lead to opti mum traffic flow conditions. In this paper, we design, analyze and sim ulate a roadway controller for an automated highway that achieves desi red traffic densities along the lane. A macroscopic traffic flow model that is modified for AHS operation is used for control design and ana lysis. We show that the proposed roadway controller guarantees exponen tial convergence of the traffic density at each section to the desired density. Simulation results are used to illustrate the effectiveness of the proposed controller and the significant benefits AHS may bring to traffic flow. (C) 1997 Elsevier Science Ltd.