Ein U-Bahn fährt am 13.08.2014 unterhalb des Alexanderplatzes in Berlin. Anlässlich der "25 Jahre Mauerfall" veranstalteten die Berliner Verkehrsbetriebe BVG eine Tunneltour zur Ost-West-Verbindung in Berlin. Foto: Daniel Naupold/dpa (zu dpa-Korr "Unbekannte DDR-Grenze: Auf den Spuren der Berliner Geistertunnel" vom 13.08.2014) ++ +++ dpa-Bildfunk +++

Those who regularly use the Berlin subway cannot avoid construction sites. Sometimes an escalator or an elevator is installed, sometimes entire stations are closed for months. On Wednesday, the Berliner Verkehrsbetriebe (BVG) invited to a construction site tour. “We want to show why some things take a little longer,” explains BVG construction manager Uwe Kutscher. The tour begins in the Jannowitzbrücke underground station, where a new exit and elevator have been installed for several years. The ceiling height of the station hall has also been increased by removing an intermediate ceiling, thereby merging two levels. Since the station, like the vast majority of subway stations, is a listed building, special design specifications must be observed in consultation with the monuments office, explains architect Martin Renz, who heads project management for stations at BVG. There are currently 20 construction sites at Berlin subway stations . The BVG spends between 150 and 180 million euros a year on the maintenance of its subway network, around 100 million euros on construction measures such as renovations or the installation of elevators. The funds come from special funds from the Senate. “We don’t have any money worries and theoretically we could spend even more money,” says BVG construction manager Kutscher. The trouble would lie elsewhere. Construction companies are currently difficult to get hold of. At the moment there are always problems with the delivery of materials, for example with the technology for elevators. There are special structural challenges at the Hermannplatz underground station. “Actually, the whole porous concrete surface should come out here,” says Kutscher. In the past, the groundwater level was lowered because of the risk of inflowing water, but today they no longer want to do that for environmental reasons. The multi-lane Hasenheide road, which runs over the station, is an additional burden. Instead of a complete replacement, the concrete ceiling is therefore being upgraded.

A construction worker explains that around 18,000 holes, one meter deep, were drilled into the ceiling for this purpose. Liquid resin is then poured through the holes, which solidifies the ceiling after it has cooled. The concrete layer is then to be sealed from the outside. The whole thing should be completed by mid-2024, the cost is around ten million euros.

The construction of an elevator also entails difficulties, as becomes clear at Bayerischer Platz. “We have to fit the elevator precisely across three levels – from the platform of the U7 to the U4 above and up to the street,” explains Kutscher. A lot of lines would also have to be rerouted.

In the meantime, 50 public bodies, associations and authorities are involved in the approval process. A consensus must be reached with all those involved. In some cases, it could take half a year for the institutions involved to submit a statement by post. “It would be better if you could coordinate more bilaterally and not everything has to be clarified centrally.” 38 of the more than 170 underground stations in Berlin still do not have elevators. With six to seven new elevators a year, says Kutscher, all train stations could be equipped in four to five years.