Waterloo International Terminal

The International Terminal at Waterloo serves the same function as an airport and it has most of the services and facilities normally associated with an airport. At the same time it remains a railway station on a constrained urban site in central London.
The roof is 400 m long, its tapering span (from 50 m to 35 m), and its narrow, sinuous plan are determined by the site and the track layout. The striking asymmetry of the trusses derives from the position of a single track on the western edge of the site, and the resulting need for the structure to rise more steeply at this point, to clear the trains.
The structure of the roof is essentially a flattened three pin bow string arch. Because of the asymmetrical geometry of platforms, the centre pin is moved to one side allowing the arch to rise steeply on the west with a shallower incline over the platforms on the east.
The skin, or cladding, on the structure raised further challenges. Because of the twisting nature of the structure, a standard glazing system would have been extremely expensive, and, involving potentially thousands of different sized and shaped components, would have made construction extremely complex and difficult to achieve within the tight time scale. To overcome this a 'loose fit' approach was adopted, in which a limited number of different sized glass sheets are used, each held in its own frame, and overlapped at top and bottom like roof tiles. They are joined at their sides by concertina-shaped neoprene gaskets which can flex and expand to accommodate turns and varying widths.