A Safety System for Zero Velocity Detection and Operator Alertness Monitoring in Rolling Stock

Abstrac t – Modern railroad applications must fulfill proper reliability, availability, maintainability and safety (RAMS) specifications in compliance with the requirements of widely accepted international standards such as EN 50126-1:1999 and EN 50126-2:2007. In rolling stock two complementary hazards with potential critical consequences for passengers and personnel arise from the inability to determine if a vehicle is in motion and from the inability to detect if the operator driving the train is incapacitated. While the probability of occurrence of both events is remote, the level of risk of such hazards is generally not tolerable. To assure an adequate safety integrity level (SIL) depending on the target application, ad-hoc smart monitoring systems, typically referred to as dead-man's vigilance devices (DMVD), are generally installed on board of rolling stocks. In this paper the safety analysis and the design procedure of a novel DMVD are described. The main elements of novelty of the proposed solution lay in its implementation, which relies on a hardware-only, potentially redundant FPGA architecture.