Software Architecture of a safety-related Actuator in Traffic Management Systems

Traffic Management Systems are used in traffic technology for propagating information from a Higher Order Control Unit to the traffic participant. In today’s systems the user interface to the traffic participant is provided by actuators like Variable Message Signs. Such information can be either non-safety-critical (e.g., traffic jams warning) or safety-critical (e.g., green arrow opening the emergency lane on the motorway). According to international and national standards, software of Variable Message Signs displaying safety-critical information has to meet distinct safety requirements.

This paper presents a general architecture of safety-related software in an actuator according to the product standard VDE 0832. It gives an introduction to the standard and the domain of traffic control. A hazard analysis is carried out and safety measures are derived. Afterwards, the corresponding software architecture is presented. Finally, a safety assessment is carried out to prove the concept.