The talk is of six Swiss engineers, all of who studied at ETH Zurich. The work of four of them pushed back the boundaries between construction and art. The works of Robert Maillart (1872 -1940), Othmar Ammann (1879-1965), Heinz Isler (born in 1926) and Christian Menn (born in 1927) set standards for the 20th century, not only with regard to technique but also aesthetically. It is very fitting that an exhibition in the "Haus Konstruktiv" in Zürich has been devoted to them. The "Haus Konstruktiv" is a museum that specialises in concrete and conceptional art. "The Art of Structural Design – A Swiss Legacy" was compiled at Princeton University by David Billington, Professor of Civil and Environmental Engineering, and probably the subject matter's most influential specialist and advocate. That the exhibition is also on show in Zurich on the occasion of ETH's Jubilee year was made possible by Zurich Financial Services, the Electricity Company of the City of Zurich (EWZ) and ETH (1).

Small country–big influence

Two generations can be said to have been brought forth by two influential teachers. At the beginning, there was Karl Wilhelm Ritter, (1847-1906), Professor of Statics, Bridge and Railway Construction at ETH Zurich, whose students Maillart and Ammann went on to become leading engineers of their age. The other two, taught by Pierre Lardy (1903-1958), ETH Professor of Structural Engineering, were Heinz Isler and Christian Menn.

Benchmarks of bridge building: Robert Maillart's bridge over the Salginatobel in Schiers from 1930 (top); Othmar Ammann's George Washington Bridge, New York (1931). (Pictures: Schiers Tourism, Haus Konstruktiv, Zurich.) large

In the presence of the two last-named, Friday before last in a filled HIL auditorium on campus Hönggerberg, Billington spoke with humour and spirit of the miracle that little Switzerland had brought forth such an amazing group of engineers. "We Americans are grateful that they did not only work for Switzerland. Their constructions are very useful to us," said Billington in allusion to the huge dimensions of Ammann's und Menn's bridges. Since the end of the 18th century, according to Billington, no more than two really new forms of art had established themselves: Photography and structural engineering. The best of the latter combined functionality and economical efficiency with the strength of aesthetical conviction. One common characteristic of great constructers was that they achieved their results using innovative approaches.

Pilgrimage destination: the Salgina gorge

For the practicians portrayed by Billington this is no doubt true. With his bridge over the Salgina gorge near Schiers in the Grisons in 1930 Robert Maillart created a masterpiece, which the American Society of Civil Engineers selected in 1991 as one of the world's thirty greatest monuments.

Synthesis of technical innovation and artistic flair: Christian Menn's Bunker Hill Bridge in Boston, finished in 2002 (top); Model of a concrete shell roof from Heinz Isler. (Pictures: Haus Konstruktiv, Zurich) large

'I always say to the engineering students: There are two things you have to do before you die," said Billington. "First of all, walk over the Brooklyn Bridge. And then go to Switzerland and look at the Salgina gorge bridge.“ It was not, by the way, the beauty of his project that won Maillart the commission but his offer, which was a lot lower than that of his competitors. It had been possible to realise the construction for 180,000 Swiss francs because Maillart had planned a pure, filigreed ferroconcrete construction, a reductionist construction that was revolutionary at the time. A self-reliantly modern style (Billington created a link here to Paul Klee), effortlessness and a masterly use of the possibilities of the material became Maillart's hallmarks.

Steely elegance

Not concrete, but steel was Othmar Ammann's preferred material. Soon after concluding his studies at ETH, he moved to New York. In 1904 the 25 year-old Ammann self-confidently took the decision to realise the vision of his teacher, Wilhelm Ritter: to build a suspension bridge between New York and New Jersey.

More than a quarter of a century later, in 1931, the time had arrived. Near the George Washington Bridge (today, one of the world's most heavily used bridges) he succeeded in bridging a width of over 1,000 metres–thereby more than doubling the record for the longest suspension bridge at the time. To achieve his goal Ammann made use of the insight that, with sufficiently heavy cable, one could do without the somewhat ponderous stiffened supports. This accounts for the elegant design of the bridge. In addition, Ammann contributed, in no small part, to the construction of the Golden Gate Bridge in San Francisco. The crowning of his work is the Verrazano Narrows Bridge (1964). It has a span of just over 1,300 metres.

Mastery of form

Today, Christian Menn continues the distinguished Swiss tradition in the USA: With the Bunker Hill Bridge over the Charles River in Boston in 2002 Menn demonstrated, once again, the state of the art in bridge construction. His idiosyndratic design of the bent Sunniberg bridge near Klosters in Prättigau, (architectural advisor: Andrea Deplazes), caused quite a stir when it opened in Switzerland in 1999. Menn was ETH Professor of Structural Engineering and Construction for a number of years.

Heinz Isler, renowned for his wilful concrete shell constructions had his eureka moment in 1955: the observation on a building site of a sodden, soggily hanging piece of sacking led him to the discovery of the "hanging-membrane reversed" method. After the shape was frozen and turned over, its shape represented the ideal shell form. This was the beginning of Isler's experiments with non-mathematically determined shell shapes. Today his unmistakable concrete roofs arch over tennis and garden centres, motorway restaurants and swimming pools.