@@taxidriver1936 no, but the trains are light and the engines powerfull. Many Metros have either too heavy trains (many North American ones) or trains too small to fit larger engines on them (London). Berlin has avoided both problems the best they could.
Back in the day they didn't let trains with graffiti on them travel around but since there is a shortage of train sets at the moment they operate also with graffiti on trains because they don't want to cause too many cancelations
You mean U5 (min 5:37). Those trains are so called small profile trains (2.4m width / lines U1 - U4) which have been fitted to a large profile line (2.65m width / lines U5 - U9) due to a current lack of large profile trains.
I left Berlin when I was a child before the fall of the wall. Do trams still stop on road and cars stop to allow passengers to disembark off the tram ?