Automatic Train Coupling: Challenges and Key Enablers

Railways are the safest and most energy-efficient means of land transportation. Unfortunately, they are less attractive than other transportation means due to the relatively high ticket prices and unreliable travel times. Both are a consequence of high running and maintenance costs and inefficient usage of the railway infrastructure. In this article, we introduce new railway applications that increase railway safety and track use. This will accordingly decrease running costs. For instance, automatic train coupling will enable trains to automatically couple when they use the same track section and to automatically separate when they are required to use different tracks. This will enhance energy efficiency, track use, and running costs while maintaining safety requirements. To enable such an application, we introduce an ultra-reliable and low-latency millimeter-wave wireless communication system, the SBDist system, which provides direct communication and ranging between trains. We show from measurement data and simulations that the SBDist system achieves round-trip latency values below 50 ms and that the packet error rate values are enhanced by using circularly polarized antennas and applying a novel redundancy scheme.