On 14/01/2012 23:22, Wolfgang Schwanke wrote:

wrote in :

For anybody who is interested in seeing some video of the U-Bahn in
East Berlin, it can be viewed here.

http://www.youtube.com/watch?v=xQOYMKNo5x0

The one thing that confuses me about this is that I noticed Giselas
and much older stock running on the same lines, whereas I thought
their width profiles were much different, requiring them to separately
operate.

You're correct that there are two "profiles" (i.e. tunnel widths) in the
Berlin U-Bahn system each with its own set of rolling stock incompatible
with the other. But "Gisela" (stock G) are not the only stock for small
profile. The small profile lines are the oldest in the system and of
course they had a number of models from the beginning. Until 1989 the
eastern half of U2 was operated with a mixture of the old AI, AII and
the then-modern G[isela]. AI being the oldest stock of them all from the
pre-WW1 era, AII from the era between the wars. I'm not sure which one
of those we're seeing in the footage. Anyway, both AI and AII were
phased out in November 1989, coincidentally only a few days before the
fall of the wall. They had already been phased out in West Berlin in the
1960s and early 1970s, respectively. So the footage is really from the
very last months, weeks or even days these types were in regular
operation.

With what did they plan to replace the AIs and AIIs, particularly the
wide-profile ones?

I also noticed what appeared to be earlier versions of Dorotas,
seemingly at Alexanderplatz.

What do you mean by "Dorotas"?

Dorota = D-class U-Bahn trains from West Berlin.

The rolling stock we see on U5 is type
EIII, i.e. reconstructed S-Bahn carriages of some of the pre-war series.
EIII is of course large profile. East Berlin's large profile material
from pre-WW2 stock was ageing (BII and BIII mostly I guess), and they
had no capacities to construct a new model, so this makeshift solution
was introduced and was the only material to be seen on U5 for many
years, until some "modern" West Berlin D stock was bought to fill the
gap in the late 1980s.

Were there any physical connections between the eastern and western
parts of the U-Bahn when the city was divided? I don't mean parts West
Berlin U-Bahn trains simply traversed East Berlin on their way somewhere
else, but where trains from West Berlin could exit onto East Berlin
territory.

I ask, because I noticed that some tracks simply stopped short of the
border, literally cut, when I visited Berlin in 1999,

Was much homologation required when BVB acquired the rail cars from BVG?

Lastly, as East Germany was part of the Eastern bloc, why did they not
eventually operate Soviet-built metro cars?

Dunno, perhaps compatibility issues.

Maybe, yes, as the Berlin U-Bahn existed before any Soviet metro opened,
so certain specs that differed had to be maintained.

It's interesting that Berlin U-Bahn trains were able to operate on the
Pyongyang Metro, however, for I would have though that the North Koreans
would have built their system more to Soviet specs, assuming that they
differed

BTW, was there ever any talk about the existence of secret U-Bahn lines
in East Berlin, the kind of which purportedly exist in Moscow, Pyongyang
or even Bucharest?