Freeway traffic control: A survey

Freeway traffic control is a broad research area, not only interesting for its applicative perspective, but also highly motivating for theoretical investigations. This research topic has been developed in the last decades by different research groups worldwide and still offers open problems and issues to tackle which may be a source of inspiration for the community of control engineers and scientists. Since the recent technological advances towards autonomous and connected vehicles suggest that a new era for road traffic is around the corner, a survey on well-established control methods for freeway traffic networks seems particularly useful now, to fix a milestone for all the researchers in the area, in order to be ready to face the challenges of the future traffic scenarios. In this survey paper, the control approaches developed in the last decades for freeway traffic control are reviewed and a bibliometric analysis on recent scientific works addressing this topic is reported.