Early works in Switzerland
On 17th March 1894, Maillart graduated from the Eidgenössische Technische Hochschule (ETH, Federal Institute of Technology) in Zürich with an engineering diploma. He was described as being 1.75m (5ft 9in) tall, of slight build with brown hair and a moustache, and wearing pince-nez spectacles.
From graduation to the end of 1896, Maillart worked for the railway construction company Pümpin & Herzog (founded 1883) in his home city of Berne.
He began by overseeing the installation of a water tunnel for the town of Stolzenmühle, some 15km south of Berne, in the canton of Berne. In 1895, he spent May to October in the design office, and then transferred to work on site on the railway branch line to Morges in the canton of Vaud on the north shore of Lac Léman (Genfersee, Lake Geneva).
On 27th March 1896, Maillart moved north from Morges to Pampigny (also in Vaud canton) to supervise the construction of the first bridge of his own design — a rail bridge of 6m span. It crossed Le Veyron brook with a single arch of mass concrete, 600mm thick at the crown. The design used concrete as if it was just a replacement for masonry.
Nevertheless, Maillart had had his first taste of bridge design and construction, and decided he had found his métier. On being recalled to Pümpin & Herzog's Berne office in September 1896, he began to look for another — more exciting — job. He was offered a post at the Städtisches Tiefbauamt (municipal civil engineering department) of the City of Zürich, where the chief engineer, Viktor Wenner, was a former employee of Pümpin & Herzog.
At the start of 1897, Maillart returned to Zürich — the centre of Swiss engineering — and took up his new post. He soon got the chance to work on a new road bridge over the Sihl River at Stauffacher in the city.
The cantonal authorities rejected a proposal for a three-span steel bridge for the site, as they thought it would obstruct the river too much in winter, when a lot of ice passes through. In August 1898, ideas for two-span steel or masonry bridges, and a single-span steel structure, were reviewed by Maillart's former ETH professor (Karl) Wilhelm Ritter (1847-1906), who was the authorities' bridge consultant.
Ritter persuaded the authorities that a two-span bridge was undesirable aesthetically, and recommended a single span concrete bridge with steel hinges at the crown and abutments. Wenner decided that the construction department would produce comparative designs for a two-span steel bridge and two three-hinge arch bridges, one of steel and one of concrete.
Three-hinge arches were then in common use for Swiss bridges. This format had an advantage in that differential settlement and thermal expansion/contraction could be absorbed without distorting the structure. Moreover, such an arch could be designed using relatively simple calculations. However, using this technique to design a concrete bridge was new.
Maillart's scheme for the last of the options — a three-hinge mass concrete arch — proved to be far cheaper a solution than the other schemes, and it was approved for construction.
The Stauffacher Bridge (Stauffacherbrücke) was completed in September 1899 and is still in use today. Its arch spans 40m and is effectively a curved concrete slab that transmits loads to the abutments in compression. The arch is 780mm deep at the crown, 940mm at the quarter span points and 720mm at the supports. Vertical cross walls support the lightweight reinforced concrete deck.
However, little of Maillart's concrete engineering is visible. Swiss architect Gustav Gull (1858-1942) was engaged to design the bridge's exterior, and he duly clad it in traditional masonry.
Perhaps sensing that he would have more freedom as a designer if he worked somewhere other than with a public body, Maillart resigned from the Städtisches Tiefbauamt. His adventures in economical designs using concrete were about to begin in earnest.
main reference RM
1901 portrait of Robert Maillart
by A Wicky, copyright ETH-Bibliothek Zürich, Bildarchiv