What is the LZB signaling system, one of the key pieces in the fatal train accident in Toledo

The LZB signaling system, used on the Madrid-Sevilla high-speed line, monitors train speed and communicates instructions to drivers. A recent collision between two trains is suspected to involve human error following a failure of this system. The incident occurred near Toledo, where the LZB system was reportedly malfunctioning, leading to a manual control situation. The line is transitioning to the more advanced ERTMS system, which aims to enhance safety and interoperability across European rail networks. Various safety mechanisms, including ASFA and automatic blocking systems, are in place to prevent accidents, but the investigation will clarify the exact sequence of events leading to the crash.