Germany train crash: Who owns Bavaria's trains?
Two trains, run by the same company, have crashed into each other on a single-track regional line in Bavaria, in southern Germany, killing at least nine people and injuring many more. The cause of the accident is not yet clear. But there is a tangled web of ownership and management of services on the commuter line.
Who owns the track?
Germany's railway lines were built in the 19th Century. Deutsche Bahn, a company that operates all over Germany and belongs to the federal government, owns the track. It is responsible for all infrastructure.
The safety and infrastructure of the track is overseen by a federal government body, the Eisenbahnbundesamt (link in German).
The Eisenbahn-Unfalluntersuchungstelle, another federal body, has opened an investigation into the events leading up to the crash.
Who operates the signals?
DB Netz, a subsidiary of Deutsche Bahn, runs railway signalling across Germany. Its most recent annual report - from 2014 - states that 424 of the 3,090 signal boxes were electronic.
On the stretch of railway line in question, however, the signal box was of an older generation, which is run by relay interlocking and requires human input. The signals were checked the week before the crash.
In case signals fail, German railways are fitted with a final safety guard to prevent crashes. Cab signalling known as PZB (Punktfoermige Zugbeeinflussung - or "intermittent train control") will set off an alarm in the driver's compartment when the train approaches a red light. If the driver does not respond by pressing a button, the train will brake automatically.
Likewise, the PZB system causes automatic braking to kick in if a train ever goes through a red light.
Deutsche Bahn have confirmed to the BBC that this measure was available on the Holzkirchen-Rosenheim line, where the accident happened.
Chris Jackson from the Railway Gazette magazine in the UK told BBC World TV the crash was "very, very unusual" because of the PZB system.
He said: "All the safety systems have to have an override for when things go wrong. There are very strict conditions for when that can happen."
Who owns and operates the trains?
Germany's train services were part-privatised in a reform programme in the 1990s. The services of the train operating companies are bought in at state level. In Bavaria this is done by the Bayerische Eisenbahngesellschaft (link in German).
Railway contracts for local and regional trains are awarded through competitive tendering. Private companies sometimes win these and pay Deutsche Bahn for the use of the track and the stations.
The companies own the trains and employ the drivers.
The trains that crashed on Tuesday morning were part of a recently built fleet. The fleet belongs to the Bayerische Oberlandbahn (BOB), a privatised train company, which operates in the Bad Aibling area under the local name Meridian.
The BOB exists across southern Bavaria. Its parent company, Transdev, is in turn owned by the French company Veolia.
Last week the BOB warned (link in German) that 10 out of the fleet of 35 trains were out of order, owing to technical difficulties. As the cause of the accident is currently unknown, there is no suggestion that this was to blame.