Deutsche Bahn train services were gradually resuming early on Wednesday after a nationwide communications failure brought operations across its network to a standstill for around two hours late on Tuesday, a company spokesman said.
The first trains began running again at around 12:30 am (2230 GMT Tuesday), before services restarted step by step through the early morning.
The disruption was caused by a fault in GSM-R, short for Global System for Mobile Communications - Railway, the digital radio system used by rail staff during railway operations across Deutsche Bahn's network.
The state-owned rail operator said the disruption had been resolved, although major delays and cancellations were expected to persist into the morning commute in some areas.
Regional and suburban rail operators run by Deutsche Bahn also said on X that services were gradually restarting, but warned that major delays and cancellations were likely to persist into Wednesday morning.
"We were able to stabilize the situation with an emergency system. We now need to determine the cause," chief executive Evelyn Palla told Bild newspaper.
IT experts had worked continuously to resolve the outage, the company said, thanking passengers for their patience.
Passengers left stranded
Many passengers were left stranded, with long queues forming at information desks in stations. Deutsche Bahn said it was providing affected passengers with taxi and hotel vouchers.
The outage affected long-distance and regional trains, as well as some commuter rail services operated by Deutsche Bahn. Berlin's entire S-Bahn network and S-Bahn services in Stuttgart were halted.
Other urban transport systems, including Hamburg's subway network, continued to operate normally.
Private rail operators were also affected. Metronom, which runs regional passenger services in northern Germany, said all of its trains had been impacted.
Freight traffic was also brought to a halt. The Association of Private Freight Railways called for a detailed review of the two-hour outage.
The cause of the disruption late on Tuesday should not be determined solely on the basis of information provided by DB InfraGo, Deutsche Bahn's infrastructure operator, the association's managing director Peter Westenberger told dpa.
Better monitoring and management of railway infrastructure operations was needed, he said.
According to DB InfraGo, the GSM-R system has replaced almost all analogue radio systems used by Deutsche Bahn and offers advantages including secure operational communication, special group calls and targeted contact with railway dispatchers.
