Simulational analysis of two controllers for variable speed limit control.

Variable speed limit control (VSLC) is one of the services from the domain of intelligent transport systems applied to alleviate or prevent congestion on urban motorways. The main idea of VSLC is to change the speed limit according to current traffic or weather in order to improve the traffic situation. Improvement of the traffic situation on urban motorways depends on the applied controller and its parameters. For this reason, the controllers chosen for implementation have to be tested in simulations using a realistic urban motorway segment, placement of sensors and traffic scenario, and a relevant set of control parameters. An analysis of two VSLC controllers, including the influence of their parameters on controller performance with respect to traffic and environmental aspects, is presented in this paper. To this end, an appropriate microscopic simulation framework was developed, the fundamental diagram of a simulated synthetic urban motorway segment was measured and traffic parameters, with vehicle emissions values, were obtained. The effectiveness of the two analysed controllers was compared based on the obtained simulation results. The results revealed that appropriate settings of the controller are crucial to ensure optimal use of urban motorways with minimum travel times and vehicle emissions. [ABSTRACT FROM AUTHOR]