Berlin鈥檚 拢170m Hauptbahnhof is the first central train station in a European capital for 100 years. It鈥檚 also a state-of-the-art update of the 19-century industrial cathedral, a hub at the heart of Europe and a stunning piece of engineering. So why did the architect end up suing its client, then?
For the past 100 years, there has been no new central train station in a European capital. All the ones constructed in that time have been rebuilds or extensions.
But Berlin鈥檚 拢170m Central Station is the genuine article 鈥� in more ways than one. It really is new, as the 19th-century station that used to inhabit the site was destroyed in the Second World War. And not only does it advance the classic form of a capital鈥檚 main station, it brings its functions into the 21st century. Further, it healed an old wound in this formerly divided city and, through considerable engineering virtuosity, was delivered ahead of schedule, and in time for the World Cup. But despite these feats, the project ended in a rancorous dispute, the resolution of which could have interesting ramifications for client-architect relationships in Germany.
The station has been developed to serve both east and west Berlin, which were rent apart after the war. It sits in the geographic centre of the city on a blighted no man鈥檚 land near the Berlin Wall, just across the River Spree from the Reichstag.
It breaks the mould in another way. All lines used to lead to Berlin and end there. Now it is not a terminus but a through station, serving 21 long-distance, suburban and underground lines as well as a bus station. Germany is in the process of reconstructing one of the most efficient railways in Europe, and part of the work involves the slow, expensive process of turning railway terminuses into through services that are truly intercity. The rail regeneration for Berlin alone carries a cost of 拢7bn. But what better transport system could there be to serve an increasingly integrated Europe?
All this makes Berlin Central Station the largest through station in Europe. With a total floor area of 175,000 m2, it caters for 1100 trains and 300,000 passengers every day. There are tracks in the air and tracks under the river. Multiple lines intersect on separate levels in a dizzying cat鈥檚 cradle. It is also a true mixed-use building, with 80 shops and restaurants and 50,000 m2 of offices.
Germany鈥檚 foremost railway architect von Gerkan, Marg und Partner took the tradition of the 19th-century terminus and updated it impeccably to the 21st. This is immediately obvious in the great barrel-vaulted steel and glass roof that stretches 321 m and curves up and over the nine elevated lines.
More than that, the architect has taken the station鈥檚 prime function as a key crossing in an integrated continent and expressed it in a cruciform shape. The cross shape comes from two rectilinear office slabs that bridge the barrel vault near its midpoint. Sandwiched between them is the main station hall, with a vaulted glass roof and glazed end walls giving views to and from the city.
Designed with structural Schlaich, Bergermann und Partner, the main roof is an inspiring update of the classic station, which captured such volumes of space and light. It has a clear span of up to 68 m but rises only 16 m to cover the trains on the top platforms, which makes it low, wide and elliptical.
The glazed shell itself is highly transparent and filigreed thanks to the 9117 panes averaging 1.65 脳 1.65 m each, which are framed in slender steel and braced externally by diagonal cables. The roof is supported at intervals on 23 slender steel arches that are braced by a series of struts and cables that march up and over the roof.
Anti-sun glass was used to curb overheating in the summer and 8.4% of the roof surface is covered in 78,000 photovoltaic cells to generate energy and provide shade. Warm air escapes through vents along the ridge and fresh air is drawn in under the eaves.
The main hall at the midpoint of the station is a large void 160 脳 40 m in area and descending to the underground platforms, giving space, daylight and views to five public floors. Fifty-four open escalators and 16 glazed lifts ferry people up and down. Ticket halls, restaurants and shops overlook the void from three floors on either side.
All in all, it鈥檚 a lively update on a classic theme. But there is one problem: it stands like a beached whale in a blighted district. That could change, however. Developer Vivico has embarked on a five-year programme to create 鈥渁 new exclusive address for offices, shops and residences鈥�.
Finally, the station鈥檚 completion in time for the World Cup is an example of characteristic German efficiency. But achieving this target involved a substantial compromise to the design, which started a row that has yet to be settled. The length of the vaulted glass roof was cut by 110 m, which led to an extraordinary court case in which the architect is suing client Deutsche Bahn, with a decision expected in September.
鈥淚f Deutsche Bahn can prove that its alterations saved costs, it can complete the station as it sees fit,鈥� says a spokesperson for von Gerkan, Marg und Partner. 鈥淚f the new plans don鈥檛 reduce cost, Deutsche Bahn should be obliged to build the station as the architect designed it.鈥� In Germany it seems that even top clients mess with architects鈥� designs at their peril.
How it was built
The construction of Berlin鈥檚 station involved everything from heavy civil engineering works to high-tech glazed vaulting.
Ground works and foundations
For the deep foundations, trained divers laid concrete base slabs underwater. To construct nine excavation pits amounting to 90,000 m2 in area, watertight diaphragm walls were installed around each pit. Then 1.5 million m2 of soil was excavated and removed by barge. Removing it by road would have resulted in a convoy of trucks 1300 km long.
But since the pits were excavated to a depth of 25 m, they filled with groundwater. So ground anchors were driven 27 m into the ground and 1.5 m thick concrete base slabs were cast underwater on top of them. Finally, the groundwater was pumped out and construction of the underground structures proceeded in the dry.
Rail viaduct
An unusual combination of rolled and cast steel and precast concrete was used to erect the high-level viaduct and two bridges 240 m and 570 m long. Eight trees of rolled tubular steel 23 m high were combined with cast joints at their bases and heads. It was the only way of constructing such a delicate structural system, and the cast steel reacts well to dynamic loads, according to project engineer Schlaich Bergermann und Partner.
High barrel-vault roof
The glazed barrel vault is a high-tech feat that took just four months to erect. A total of 23 steel roof trusses were raised on 3600 tonnes of temporary scaffolding to create arches up to 68 m wide and 16 m high. An added problem was that, as the vault curves and widens towards its centre, none of the 9117 glazed panels are identical, and the design relied on computer-aided manufacture. The steel frames to the panels were welded together on site and tensioned by diagonal external cables. As they made up a stressed skin that is vital to the structural stability of the vault, the scaffolding could not be struck until the panels were fully fixed.
Office bridges
The two rectilinear office slabs were swung into place over the main barrel-vaulted roof in an extraordinary action like the closure of a bascule bridge. The horizontal steel bridge structure for offices was split into two halves and erected vertically to a height of 70 m on either side. Then both halves were lowered to meet in the middle.
Key points
- New central station for European capital city planned as rail intersection rather than dead-end terminus
- Rail intersection clearly expressed in station鈥檚 cruciform shape
- High-level platforms sit beneath a 321 m long barrel-vaulted roof of steel and glass
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