Basque underground.

One of the key components in renewing the Basque capital is a new metro line which, often using the latest tunnelling technology, offers a string of impressive stations which add to the placedness of the urban spaces above.

No vigorous modern city can afford to be without a mass-transit system of some kind. The alternatives are Los Angeles or Jakarta, and no self-respecting urban administration can be prepared to accept either of those grim fates unless forced to by lack of cash or a malign central government.

Bilbao suffers from neither of these problems. As capital of the Basque autonomous region of Spain, it is one of the most lively cities in Europe, undergoing a renaissance. Few European cities have been as adventurous or far-sighted. Numerous cultural initiatives have been set in motion (for instance the Guggenheim Museum by Frank Gehry), but clearly such one-off buildings will not of themselves regenerate the rather run-down industrial city. New infrastructure was needed, and while the port and many roads have been upgraded, much of the main infrastructural investment has been in a new metro. In 1988, the Basque government held a limited competition for the design of the system. Sir Norman Foster & Partners (now Foster and Partners), in association with civil engineers Ove Arup & Partners, and quantity surveyors Davis Langdon & Everest, won with a proposal that was held to be both clear and aesthetically appropriate.

The underground system will eventually link the port, fishing villages, city centre, industrial zone and suburbs, catering for the million inhabitants of greater Bilbao. The first phase runs south-east from the centre, roughly following the course of the river valley. All 11 stations in this phase are underground, though when the full system with its 29 stations is up and running, 15 of them will be on the surface. Nine of the completed stations are built to a standard formula, which is varied in its approach routes according to circumstances of the city overhead. The 16m wide station caverns are formed using the new Austrian tunnelling method.(1) Precast concrete panels (1.2m x 2.4m) form permanent shuttering to the in-situ concrete and associated waterproof membranes. At each end of the caverns a mezzanine is slung over the tracks, with its high-temperature stainless-steel structure hung on ties from the roof of the cave. Escalators connect directly to the surface from the mezzanines, and passengers are conducted down to the platforms on each side by stairs that gently and elegantly curve against the cavern walls (people with mobility problems can use lifts).(2) The visual intention is to allow the full volume of the caverns to be appreciated as much as possible, and in the middle of each station where there are no mezzanines the stratagem works very well, though at the ends (particularly at rush hours) the space sometimes seems a little crowded, both vertically and horizontally.

To anyone from London, where the usually old and often grubby stations are invigorated by a profusion of lively advertising posters, the Bilbao caverns seem a bit austere and empty. All the signage (developed by Otl Aicher and carried out by Michael Weiss Associates) is clear and very carefully controlled; the few instructional posters allowed are carefully grouped under the station labels. But how do you pass the time when waiting for a train?

This sterile quality is totally absent at street level, where the escalators emerge under glass canopies which rise out of the street floor with great elegance and smoothness. This is our fin-de-siecle equivalent of the famous entrances to the Paris Metro designed by Guimard a century ago: like those, the Bilbao ones use the most advanced glass technology available to offer an urbane sense of welcome and arrival. They are rightly memorable elements of the cityscape, without ostentatiously drawing attention to themselves like for instance the vulgar proliferation of stridently mediocre telephone boxes that have swept across London and are poised to invade the Continent in the name of competitive telecommunications.

Two of the initial 11 stations are formed by cut-and-fill methods rather than tunnelling. Of these, the most dramatic is Sarriko, which has a much grander entrance than the others: a big curving wedge of glass pours out of the ground to welcome passengers and pour light down into the huge trench. The escalators move through the great shaft of light to a concrete mezzanine which covers both track and platforms, a sequence of almost Piranesian sublimity, though whether its drama will be appreciable in a wet winter rush-hour is doubtful.

1 No shield is used, hence oval sections are obtainable. Small parts of the proposed section are progressively excavated and reinforced laterally and/or tied back to the rock matrix as circumstances require.

2 A lift in each station also runs from street to platform levels.