A. Hegyi, T. Bellemans, and B. De Schutter, "Freeway traffic management and control," in Encyclopedia of Complexity and Systems Science (R.A. Meyers, ed.), New York, New York: Springer, ISBN 978-0-387-30440-3, pp. 3943-3964, 2009.
The goal of this chapter is to provide an overview of dynamic traffic control techniques described in the literature and applied in practice. Dynamic traffic control is the term to indicate a collection of tools, procedures, and methods that are used to intervene in traffic in order to improve the traffic flow on the short term, i.e., ranging from minutes to hours. The nature of the improvement may include increased safety, higher traffic flows, shorter travel times, more stable traffic flows, more reliable travel times, or reduced emissions and noise production. The tools used for this purpose are in general changeable signs (including traffic signals, dynamic speed limit signs, and changeable message signs), radio broadcast messages, or human traffic controllers at the location of interest. Moreover, currently the possibilities of assisting, informing, and guiding drivers via in-car systems are also being explored. The term dynamic traffic management includes besides dynamic traffic control also the management of emergency services and non-automated procedures (such as the implementation of predefined traffic control scenarios during special events), typically performed in traffic control centers. However, in this chapter the focus is on automatic control methods. Furthermore, this chapter deals exclusively with dynamic freeway traffic control techniques.