STATION MASTER.

The glazed train shed is having a revival as one of the most important elements of modern ecologically conscious cities. In Berlin, this one sets standards of size, simplicity and elegance.

At the 1996 Venice Biennale, there was a show of projects by German Rail entitled the Renaissance of the Train Station. It was a celebration of the privatization of the Deutsche Bahn AG, the most wonderful train service in Europe, clean, comfortable, meticulous, relatively cheap, frequent and almost always on time. The show was a reminder and evocation of the great days of rail travel in the late nineteenth and early twentieth centuries. At the same time it was an advertisement of future intent: to make the railway station once again part of the public realm; to make it a celebration of arrival and departure; gateway of the city. Much of what was on display in 1996 was devoted to re-exploring the potential of the great glazed train shed: the luminous arcade which leads us to the carriage door.

The new Spandau station in Berlin by von Gerkan, Marg & Partner is the first built result of the programme. On the main line between the new German capital and Hanover, the glass vaults are very close to the suburb's town hall. The architects claim that their main shed is probably the longest glazed hall in the world at the moment, but as we all know, size is not everything. Spandau station, as well as being big, is a generous space, welcoming and dignified.

And for all its seeming simplicity, it has been rather complicated to make. Curving rail tracks made the geometry of what is essentially a simple parti: a long parallel pair of glazed vaults carried on Y-shaped central columns, into a subtly complex figure, in which each pane of glass has slightly different dimensions.

Grimshaw and engineer Anthony Hunt had to cope with a volume which was caused to taper in both height and breadth by the nature of the tracks and site; and it had to accommodate some quite extraordinary movements in flexion caused by the very heavy international trains rolling over the old brickwork viaduct underneath. The Spandau building did not have to taper in height, so it can have regular vaults formed as virtually simple arcs. Both buildings are rational, but in Berlin the spirit is Rationalist, while in London Organic is the ethos.

Comparisons are inevitable with Grimshaw's London Waterloo International terminal for Channel Tunnel services (AR September 1993). Computerized analysis, cutting technology and logistical assembly are similar, but the results are very different.

At Spandau, secondary arches bear on longitudinal beams (which also act as gutters) which span between the Y-shaped columns set at 18m centres. Vaults are held together and stiffened by an internal diagonal grid of stainless steel cables connecting the screw-fixed stainless steel bosses which form each junction in the roof. Roofs are entirely glazed, apart from metal strips which run along the apex of each vault and provide ventilation. Cantilevered uplighters set 3m apart provide multiple reflections on the glass, making the place more crystalline and magical at night. Small structures on the platforms, waiting rooms for instance, are executed in glass and steel with the Rationalist rigour that informs the main structure.

Platforms are 5m above street level; in the podium beneath, there is a cross street with ticketing, shops and services spanned by the bridge construction of the platforms and tracks. A wave-form ceiling allows for the different heights determined by the structure. The shape is intended to increase the apparent volume of the undercroft, but it inevitably seems rather troglodytic (though well lit), not a bad thing in itself, for the spatial compression of the entry helps enhance the airy luminosity of the glass vaults when you approach them up the escalators.