When the Berlin wall came up the city was suddenly parted into two separate parts. But the original infrastructure of the city was made for a united city hence the subway system went from West Berlin to East Berlin and then back again to West Berlin. This created a strange situation. The U6 and U8 subway lines plus an S-bahn line were all important parts of the public transport of West Berlin and if these lines became unavailable the public transport of West Berlin would be much more difficult with huge detours.
In the end these lines all remained open for the entire time of the Berlin Wall but the stations in the Eastern part of the city was closed down. The signs which used to indicate there was a station on the street level were taken down and the entrance gates were sealed off. The stations were dimly lit and the trains would drive slowly by the stations without stopping. On the subway maps from West Berlin the stations were indicated as stations where the trains do not stop. On the subway map of East Berlin the stations simply did not appear.
The separation of the city meant there were many difficulties with the running of the lines there was only limited access for maintenance workers from the west. In case a train broke down on the part of the line within East Berlin the passengers would have to wait for a the East German border police to arrive so they could escort them back to West Berlin.
The stations in the east were heavily guarded by East German Border patrols making sure nobody escaped from the east along the tracks to the west. There were border guards stationed inside bunkers at the station who could shoot at anybody trying to cross to the west. Whoever the border guards themselves was considered flight risk as well so the bunkers were locked from the outside and the border guards could not get out before somebody opened the doors. This meant certain safety risk – in case of a fire on a station the border guards would be unable to help with the situation or even save themselves from the fire. In general the standard safety features off the subway lines were suspended in the east. The emergency escape doors from the subway line were locked from and impossible to open from the inside of the subway lines – hence in case of an accident these stretches of the subway system were a death trap.
When we visited Berlin we stumbled on these ghost stations by accident. We were taking the subway line to the Nordbahnhoff which was one of the ghost stations. At the station there is a little museum with a lot of information about the ghost stations and how they were operated during the time of the Berlin Wall. We have a look at the many information boards with the story and spend a bit of time before we actually get out of the station.