Advancing Freight Train Integrity Monitoring for Next-Generation Railway Signaling Using UWB Ranging

Reliable train integrity monitoring is crucial to enabling the implementation of state-of-the-art railway signaling and safety systems such as ETCS Level 3. However, train integrity monitoring presents a significant challenge for European freight trains, which currently consist of unpowered freight wagons and a locomotive, with only mechanical and pneumatic connections between them. This paper presents a study and experimental evaluation under static and dynamic conditions of the feasibility of using Ultra-WideBand (UWB) ranging to monitor train in-tegrity with a network of low-power and cost-optimized Internet of Things (IoT) devices. Static tests are performed on freight wagons to investigate the optimal UWB sensor positioning and the impact of Non-Line-of-Sight (NLoS) conditions on ranging accuracy. These tests show that positioning has a significant impact on the proportion of ranging attempts that are successful, with an error rate of less than 4 % in the best case and over 90 % in the worst case. The standard deviation of the UWB ranging is 0.03 m in the best case in LoS conditions and 1.26 m in the worst case. The dynamic tests show that coupling and uncoupling can be successfully detected using a combination of UWB and an Inertial Measurement Unit (IMU), and that a network of self-contained UWB sensor nodes is well-suited to monitoring train integrity compared to other approaches such as Global Navigation Satellite Systems (GNSS) that rely on external infrastructure.