To be more specific, the C151s are 24 years old, the C651s are
16 years old and the C751Bs are 9 years old.
Hmm the C151 (Series 0/100) are made from 1986 to 1989. Span of
four years.
Siemens wise an absence of the builder's plate would abstain an
actual age, but we do have 1994 as a gauge.
C751B (Series 300) also range from 1999 to 2001 if I am not
mistaken.
Doors on our trains are called 'hanging type slide doors', means
the mechanism to move the doors are entirely above, the sill below
is for guiding. This is why you would see the door 'popping' in and
out, air pressure and vibration can cause this.
For extra info, domestic commuter trains in Japan have disused
hanging types for many years, due to accidents where passengers are
crammed on a train, force exerted against the door caused the doors
to pop open momentarily, and fatalities have occurred in the past
due to this. Doors are totally built to integrate with the train
frame for the subsequent designs, so the door is guarded by the
larger door frame and are unable to pop outwards. For doors on the
Shinkansen trains, there are gas operated pushers to push the door
outwards against the door frame, so a relatively air tight
environment can be achieved.
