Modeling of network level system-optimal real-time dynamic traffic routing problem using nonlinear H ∞ feedback control theoretic approach

A new method for performing network-wide real-time Dynamic Traffic Assignment/Dynamic Traffic Routing (DTA/DTR) using feedback control approach is presented. This method employs the design methodology for nonlinear H infinity feedback control systems, which is robust to certain class of uncertainties in the traffic system. The proposed real-time routing approach aims at achieving system optimum defined as the determination of the time- dependent flows that minimizes the total travel time on the network over a finite period of time. The modeling paradigm of nonlinear H infinity approach is an exact match with the requirements of a network-wide DTA/DTR problem applicable to advanced traffic management/information systems, mainly because it is computationally very efficient. The numerical evaluation of the designed feedback controller requires very simple algebraic operations that can be easily done in real- time. Moreover, the feedback control theory provides an efficient way of incorporating the information on the current network conditions obtained from traffic sensors into the control decisions made in order to drive the network conditions to the desired criteria, such as system optimality. The theory developed for network-wide problems is applied to a sample network to illustrate the application of the modeling framework presented in the rest of the article. Simulation based evaluation results of the traffic control law derived using the proposed network-wide H infinity approach are also presented.