original_query: What is the purpose of the PZB train safety system?
query: What is the purpose of the PZB train safety system in Germany?
answer: The PZB train safety system in Germany is mandatory for nearly every train and most railroad lines. It has functionality similar to other train safety systems and protects trains by triggering forced braking if a train passes a signal showing 'halt' (Hp 0) or certain distant signals.