Konzeption einer algorithmischen Einbindung neuer Regellogiken in die Funktionsbereiche von Streckenbeeinflussungsanlagen

RWTH Publications (RWTH Aachen)

Abstract

Variable speed limit systems affect traffic safety and flow during busy periods by setting speed limits on variable message signs. However, current threshold based control methods are limited to detecting the local traffic state and assigning a predetermined speed limit. These algorithms represent an open feedback loop without matching the intended control objectives with the actual impact on traffic flow. This work addresses the question how the scope of variable speed limit systems can be extended by algorithmically integrating the principles of a closed feedback loop, thereby increasing their effectiveness with the current technical equipment. The literature review in this work explores the current state of research on control technology solutions. A statistical analysis of empirical individual vehicle data is carried out to identify relevant patterns and correlations regarding the impact of variable speed limits and the compliance behaviour of road users. Based on this, the new control logic is developed in an iterative process. Finally, the control logic is tested for its potential effectiveness through simulation. The control logic enables early preventive intervention in a closed feedback loop based on new control variables. When traffic volumes are low, it responds with minor interventions, and when congestion increases, it imposes further restrictions on the speed limit. If there are no effects, the measures can be adjusted accordingly. Unlike previous methods, the control logic derives its control objectives from the traffic states of the entire route. It enables an expanded perception perspective to road users and supports their optimal behaviours. This means anticipatory deceleration at the tail end of a congestion, safe passage through the disrupted section and rapid acceleration at the head of congestion. The alignment of speeds between lanes in anticipation of increasing density is an effective action to prevent congestion. The modular structure of the control logic ensures good traceability of decisions and facilitates the integration of additional influencing measures. All parameters can be easily derived from traffic contexts. As a result of this work, a conceptual control logic based on closed loop control principles has been developed which integrates existing variable speed limit measures. In simulation, the control logic successfully reduces the spatial and temporal spread of congestion as well as the frequency of speed reductions. The control logic is conceptually aligned with a route management system. In the future, this will also be essential for making use of vehicle-to-infrastructure-communication. The principle of simultaneously influencing vehicles within a section could even be simplified. The control logic can easily be implemented into existing system architectures, since it does not demand any additional requirements for roadside equipment. Consequently, it will increase the effectiveness of variable speed limit systems.

Authors 1

1. Jessica Hegewald corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen