Frankfurt gateway.

Through its fluid form and organizational clarity, this new railway station at Frankfurt Airport aims to ease the chaos and congestion of one of Europe's busiest air terminals.

Since 1955, Frankfurt International Airport has been Lufthansa's home base. It is the eighth largest airport in the world, the most important one on the European mainland and gateway to the Continent for other international airlines. Over 40 million passengers annually pass through this vast complex of overlapping and interconnecting surface and air, local, national and international transport networks.

Der Spiegel magazine has called Frankfurt Airport a 'Monster ... the impossible airport'. Air travel has doubled in the last decade and is forecast to grow by at least 5 per cent annually. Not least of the problem is how to deal with transport links on the ground. The existing railway station in the basement levels under the airport has been an important element in this passenger servicing system.

While it will continue functioning for district and intercity diesel trains, a new station terminal by BRT Architekten has been built for the latest generation of high-speed electric trains. Consisting of 38 000 sq m of public and technical service areas, it forms a key part of the modernization and extension programme for both German Railways' national network and Frankfurt Airport.

In the wake of several competition wins for German Railways, Hamburg-based BRT Architekten are gaining a modest reputation for a combination of tectonic expression and fluid morphology. The new station occupies a site above ground, parallel to the airport and associated congress hotel, but on the opposite side of an intervening autobahn. The 700m long curved edged body of the station floats on pairs of splayed telescopic aluminium clad columns over partially sunken tracks below. As an autonomous structure it is linked to the airport terminal's departures and arrivals by a high level covered footbridge, a flattened rib cage of steel clad in aluminium, which cuts through the congress block and over the adjoining motorway.

Arriving under an oval glass dome on the roof of the station, passengers ride escalators down through a light-well to the trains. The 60m clear span concrete structure, roofing two platforms and four lines, is open to daylight and natural ventilation between the supporting perimeter columns. Waiting and alighting areas on the platforms are colour coded using light and dark reconstituted stone. A silver aluminium soffit folds around the enclosed station areas above. Sandwiched between roof dome and platform levels are 7500 sq m of lounges, planned for Lufthansa and railway club class passengers, and the ubiquitous shopping facilities.

The roof level arrival hall under the dome is spectacular. An uninterrupted 360 degree panorama of sky can be viewed through the canopy of glazed panels suspended internally from steel arched ribs, The glazing blocks are designed to reduce glare, but there is still enough light to bounce off the St. Baudille limestone flooring and filter down into the well of the spaceship below.

The station is only the first stage of site development. Frankfurt Airport Authority, who own the air rights, are planning to top it with an entertainment centre. Foundations and superstructure can support another six double-height or 12 single storeys. It is proposed to enclose these additional functions under one homogeneous membrane, so maintaining the sleek, tubular airship form.

Architect BRT Architekten (Boche, Richter, Teherani), Hamburg

Project team Berthold Staber, Christian Feck, Lutz Gnosa, Frank Gorge, Michael Horn, Wolfgang Labsch-Boga, Katja Pahl, All Pakrooh, Monika Pfretzschner, Claudia Springmeier, Peer Weiss, Christopher Wilford, Arndt Woelke, Katrin Koulouri, Irene Manhardt, Ulf Schroder, Jurgen Wilhelm

Structural engineer Binnewies

Services and lighting consultant HL-Technik

Computer generated images Datenland, Erik Recke