[TheHippo]

I don't know. The Berlin train system is known for stopping to work if its either to hot, to cold, to windy or to rainy.

[tehabe]

This is about the subway (U-Bahn), not the rapid transit (S-Bahn), the latter had serious issues with maintenance a couple of years ago.

[nealmydataorg]

I recall that before unification(in West Berlin) S-Bahn trains used to be older and U-Bahn trains were newer. I do not know current state of comparison between U-Bahn and S-Bahn trains.