THE ROOF DIPS AND SWOOPS ALMOST IN DEFIANCE OF THE ARCHES
The journey from Berlin's new central station, the Hauptbahnhof, to the city of Dresden takes just over two hours, but in terms of the architect/client relationship the two stations are a universe apart.
When I arrived in Berlin, the German courts had just ruled in favour of architect Meinhard von Gerkan in his battle with the Deutsche Bahn railway company over the integrity of his design for the Hauptbahnhof. The court ruled that Deutsche Bahn had tampered with the design, and ordered that remedial work should begin on the building, which only opened last summer, 13 years after the commission was originally won.
In stark contrast, Foster and Partners' newly refurbished Dresden Haubtbahnhof railway station had its grand opening late last year, and illustrates the practice's ability to roll with the punches of a tricky and unpredictable design process. It is now nine years since the architect's appointment and, despite having to contend with the client's changes of mind, a difficult phased process and the record oods of 2003 - which happened just months before the refurbishment of the reception building was due to start on site - the station is open and, broadly speaking, a success.
The process here has been of a lower profile than that of the Berlin Hauptbahnhof, but has still been hugely important to Dresden's identity. The station, which was designed by Ernst Giese and Paul Weidner, was originally completed in 1898 and, although heavily damaged, was one of only a few major buildings to survive the Second World War firebombing of the city. It has an unconventional layout: the largest train shed acts as a terminus in the centre, with two smaller halls to the sides accommodating through trains on elevated platforms - Dresden is on the main line running between Berlin and Prague. The original reception building is a highly eccentric confection with a glass lantern - now restored to its former glory as part of the Foster scheme - which sits on top of a a strange, faintly Art Nouveau facade, anked by two castellated towers.
Unusually, the main entrance to the station is not through this grand eastern portal, but from Wiener Platz to the north, across which is Prager Strasse and the main route to the historic centre of the city, which sits on the banks of the Elbe river. Most users enter through the long facades that pass underneath the elevated platforms to the main concourse.
Foster and Partners was appointed to the station in 1997 and the project has proceeded in an intermittent fashion. The first phase, which began on site in 2001, was the construction of the Te on-coated glass-fibre roof over the train sheds. At 85 million euros (£57 million) it was the most expensive part of the scheme, and is also the most spectacular. Although the original train-shed roof was destroyed in the Allied firebombing of 1945, the 19thcentury iron arches remained almost completely intact, and only required a minor amount of cleaning and repainting before they could be re-covered.
Spencer de Grey, senior partner at Foster and Partners, explains that the decision to use a translucent roof was made for both cultural and practical reasons. 'The original roof covering had a lot of glass in it and we wanted to get back to the feeling of natural light, ' he says. 'The Teon-coated fabric lets in 15 per cent natural light. It is also lightweight, and with the cast-iron structure there was a limit to how much weight it could actually take. We felt it was the appropriate solution.'
The lightness of the glass fibre meant that not much further support was required, just some subtle cross-bracing between the arches. In order to emphasise the station's three spectacular vaults, that span 59m in the central hall and 37m in the north and south halls, 67 slit skylights have been created directly over the arches.
The fabric meets the piers of the vaults in a hugely successful way. At the 'V' point of two arches the roof is gathered together in small funnels, reminding me of Anish Kapoor's Marsyas installation at Tate Modern in 2002. The roof dips and swoops, almost in defiance of the arches as much as in sympathy, to the point where it seems as if the arches are tethering down the fabric rather than supporting it.
Besides the functional justifications, there is a certain circus jollity to this historic building - from the towers to the steel footings of the piers that are decorated with scrollwork - that the elegant marquee of Fosters and Partners' train shed is in complete accordance with. Press information from the practice likens the cruciform plan of the concourse building to a grand basilica - but it's much more fun than that.
The reconfiguration of the interior of the reception building - the second phase of the project that began construction in 2003 - emphasises the building's T-shaped arrangement. This 'T' is retained as the main concourse space, with small retail units behind restored walls in polite beige plaster. The two 400m 2 waiting rooms on either side of the trunk of the 'T' were severely damaged during the war, one receiving a direct hit by a bomb.
Both rooms were made good during the Soviet era, but have now been subjected to a bit of Foster and Partners' archaeological-style rehabilitation. They now feel more like courtyards than rooms, with the brickwork cleaned to within an inch of its life while still retaining the scars of the damage it received. De Grey compares this approach to the Reichstag and to the Great Court of the British Museum, where smoke damage on the western facade is still visible. 'We didn't want to make it an immaculate recreation, ' he says. It may not be a recreation, but it certainly is immaculate.
The problem lies with the glass roofs. They have a slight pitch, but not enough to give them any character. It's a shame, as the rigour of the approach here is impressive. The sourthernmost of these courtyards hosts a market-like restaurant that suits the rough brick walls, but the same can't be said for the ticket office, which is occupied by over-branded Die Bahn ticket counters. Other grand rooms in the concourse include a waiting room which overlooks the train shed and some restaurant units of impressive scale. That one of them houses a Burger King is an irritation, but it must be the grandest burger restaurant in the former Eastern Bloc.
The project's only failings begin where the work of the architect stopped. The surrounding urban strategy, which was beyond the remit of Foster and Partners' work, is under-resolved, and has not dealt at all with how the station addresses neighbouring Wiener Platz to the north. The square itself is a contemporary-style wasteland, with a few banal lamp posts and glass pavilions that provide access to a underground car park.
It is possible that the next phase of Foster and Partners' work will be able to address this by rebuilding the retail space underneath the station's elevated platforms, but I remain sceptical about whether this will provide enough life to save it. Likewise, the bridges across the plaza in front of the station are awful, built in clumsy stoneclad concrete. Bridges of steel would have echoed the ironwork inside or referred to the iron structures that characterise the SBahn elevated railways of Berlin, and would have proved much more successful.
Inside there is a feeling that the building has not quite been finished properly. A major problem is the night-time lighting.
In the train sheds simple pendant lights hang high up at the top of the arches, providing a pleasant light but failing to fully highlight the drama of the white soffit. Judiciously placed lights at the dropping points of the plastic roof do add a certain accent, but the undersides of the vaults are not lit at all, which seems something of a shame. With all that white surface, some indirect lighting would have been appropriate, and the north and south sheds are barely lit at all.
Another curious omission is lighting within the reconstructed glass cupola. The cupola is part of the naturalventilation system, and a transparent ETFE cushion separates it from the main volume of the station reception building. However, because it is not lit from within, it is rendered invisible at nighttime - a missed opportunity, which is much, one senses, to de Grey's chagrin.
It seems a shame that in a building this eccentric, the handrails and balustrades couldn't step beyond the glass and brushed-stainless-steel uniform that has become so predictably characteristic of Foster and Partners' work. But the restrained planning suits the building perfectly, and the train shed is quite unlike anything I have seen. It has the confidence of Foster's best recent work - the Millau Viaduct, for example, where the intoxicating context has not restrained the architect from doing something spectacular and subtly authored. Foster and Partners has succeeded in adding another layer of joyful eccentricity to this strange and beautiful building.
One of the design challenges for Munich-based designer Schmitt Stumpf Frühauf, which worked with Buro Happold as the specialist for the fabric roof, was to resolve the load transfer from the fabric membrane through the existing steelwork into the foundations.
This was achieved by introducing a secondary 'transfer' structure to convey loads from the membrane to the top chord of the old steel arches. The fragile arches have little resistance to horizontal forces; therefore the reactions in longitudinal direction of the station are transferred to the braced end bays, which act as 10m-wide trusses.
To allow for catastrophic load cases (eg. partial or total membrane failure) additional cables have been introduced underneath the fabric to make sure that the overall stability is maintained. The complete change in the type of roof cladding made it necessary to reconsider the whole structure of the station hall and its elements.
The introduction of a load-bearing membrane skin makes the use of secondary purlin members unnecessary. The use of a double-curved membrane surface creates the required stiffness to span the maximum distances between the arches without any additional intermediate supports between the new secondary steelwork.
As only pairs of arches are linked with rigid purlins, and the spaces in-between are linked by the exible membrane, the whole structure is able to ex slightly to accommodate the elongation of steel structures due to temperature changes. The construction sequence also presented a challenge as the arches (with the exception of the braced end bays) cannot resist the horizontal forces induced by the prestress of the membrane. It therefore was concluded that temporary struts at the level of the top chord of the arches would provide support during construction. Only after the very last panel of the membrane is installed and prestressed can these temporary struts be removed.
Cost 85 million euro (£57 million) budget for membrane roof; 55 million euro (£37 million) budget for reception building Client Deutsche Bahn AG Station & Service Architect Foster and Partners: Norman Foster, Spencer de Grey, Christian Hallmann, Stanley Fuls, Florian Boxberg, Patricia Fairclough, Anja Flesh, Felix Forthmeyer, Christina Gresser, Klaus Heldwein, Tom Mival, Yohko Mizushima, Virginie Mommens, Uwe Nienstedt, Sven Ollmann, John Prevc, Michael Richter, Axel Rostock, Diana Schaffranek, Marc Schwabedissen, Bernd Treide, Inge Tümmers Structural engineer Buro Happold (membrane roof); Schmitt Stumpf Frühauf & Partner (existing building) M&E engineer Schmidt Reuter & Partner (membrane roof); Zibell Willner & Partner (reception building) Cost consultant BAL GmbH; Schmitt Stumpf Frühauf & Partner Project management AYH Homola GmbH & Co KG (membrane roof); Kaiser Baucontroll (reception building) Historic buildings advisor ADB Lighting consultant Speirs and Major Associates