"The Railroad Bridge over the Aare near Busswyl"

Die Eisenbahnbrücke über die Aare bei Busswyl auf der Berner Staatsbahn zwischen Bern und Biel. (Zürich : Meyer & Zeller, 1868). Folio (46,5 x 30,0 cm).

acquired in 2018

One of the 20th century's leading bridge-builders was born a scant three kilometers away from the Iron Library. Othmar Ammann, who was born in Feuerthalen in 1879, emigrated to the United States in 1904, where he became the "father of the largest bridges of New York City" and one of the most influential bridge engineers. Among his achievements, he was consulting engineer for the construction of the Golden Gate Bridge in 1937 and responsible for planning the spectacular Varrazano Narrows bridge in New York in 1964.

But let's go back from the Hudson River to the Aare, from New York to Busswil. Our aim is not to talk about the literature on Othmar Ammann that you'll find in the Iron Library but about a book on bridges from his native land. The bridge is not particularly spectacular, and at first glance the book, too, is rather modest. There is no author's name and hardly any text, only a few explanations scattered among the plates.

The plates contain overview plans, a graphic representation of the progress of construction, illustrations of the foundation equipment and caissons, details of the latticework, a free body diagram, and details of the construction costs. The four-span lattice truss bridge over the Aare, with a total span length of 171 meters, was built near the village of Busswil (close to Büren in the canton of Berne) in 1863-64 – in the book presented here the village is still known as Busswyl; it merged with the neighboring town of Lyss in 2011. The bridge is the most important engineering feat on the railroad line between Bienne and Berne opened on 1 June 1864.

It should be seen in the context of the various lattice truss bridges for railroads built in Switzerland under the influence of Karl von Etzel (1812-1865). Karl von Etzel joined the Swiss Central Railway as chief engineer in 1852. An overview of the bridges designed and built under von Etzel's guidance can be found in the illustrated volumes "Bruecken und Thaluebergaenge schweizerischer Eisenbahnen" published between 1856 and 1859. The bridge over the Aare at Busswil is not illustrated there.

There is still a railroad bridge at this spot but the situation is completely different from what it was in 1864. Four years after the bridge was finished, work on the Jura Water Correction began, profoundly  altering the landscape. The Aare, which regularly posed a threat of flooding until then, no longer flowed under the railroad bridge but had been diverted via two canals to flow into Lake Bienne. The "Old Aare", a harmless tributary, remained in the old river bed under the bridge but was no longer much of a challenge for bridge engineers.

The bridge's construction manager was Friedrich Gustav Gränicher (1820-1879), who had worked with Karl von Etzel and was appointed Chief Engineer of the Bernese State Railway in 1861. Nikolaus Riggenbach (1817-1899), mechanical engineer and director of the Main Workshop of the Swiss Central Railway in Olten, was responsible for the machinery and iron parts, while the company in charge of excavation works and masonry was Locher & Cie. Switzerland is "bridge country", and among its 8,000 railroad bridges there are many that are older, longer and higher than that over the Aare at Busswil.

But this bridge also sets a record even though this record is literally hidden underground: it is the first bridge in Switzerland whose foundations were built with pneumatic caissons, i.e. caissons lowered into the river bed and filled with compressed air (Encyclopädie des gesamten Eisenbahnwesens, Bd. 1, p. 467).

The core of the description of the book was kindly provided by the antiquarian bookseller Meinhard Knigge (Hamburg), from whom the Iron Library acquired the volume.