The Brusio spiral viaduct (or Brusio circular viaduct; it, Viadotto elicoidale di Brusio, german: Kreisviadukt Brusio) is a single-track nine-arched stone spiral railway viaduct on the

Bernina Railway The Bernina Railway (german: Berninalinie; it, Linea del Bernina; rm, Lingia dal Bernina) is a single-track railway line forming part of the Rhaetian Railway (RhB). It links the spa resort of St. Moritz, in the canton of Graubünden, Switze ...

. It was opened on 1 July 1908. A key structure of the

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

-listed Bernina Railway, it is located near

Brusio Brusio (Lombardy, Lombard: ''Brüs'', Romansh language, Romansh ''Brüsch'') is a municipalities of Switzerland, municipality in the Bernina Region in the Cantons of Switzerland, canton of Grisons in Switzerland. History Brusio is first mentioned ...

, in the Canton of Graubünden, Switzerland, and was built to limit the railway's

gradient In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gr ...

at that location within its specified maximum of 7%. It is considered to be one of the architectural highlights of the

Rhaetian Railway The Rhaetian Railway (german: Rhätische Bahn; it, Ferrovia retica; rm, Viafier retica), abbreviated RhB, is a Swiss transport company that owns the largest network of all private railway operators in Switzerland. Headquartered in Chur, the Rh ...

Location

The Brusio spiral viaduct forms part of the Bernina Railway section between

and Campascio railway stations. It is just south of Brusio, and approximately from St. Moritz railway station.

History

During the construction of the

, its engineers decided that its route and features ought to follow and adapt to the natural landscape to the maximum extent, avoiding unnecessary complexity wherever possible. They also decided to avoid the construction of a rack-and-pinion railway due to a desire for the line to be suitable for both passenger and freight traffic; the adoption of a rack system would have made it impossible to run heavy trains, effectively preventing the line's use by freight trains. It was also desirable for the line to serve valley locations, and thus for the route to vary in height above the valley floor. It was such decisions that drove the construction of the Brusio spiral viaduct. Brusio Viaduct (158241421)

A spiral viaduct was required immediately south of Brusio to limit the railway's

grade Grade most commonly refers to: * Grade (education), a measurement of a student's performance * Grade, the number of the year a student has reached in a given educational stage * Grade (slope), the steepness of a slope Grade or grading may also ref ...

to the required maximum of 7%, so that the train would not slip on the way up, or be uncontrollable on the way down. The construction of a viaduct on this site had not been originally planned for; instead, a spiral tunnel was at one point intended to be constructed; however, local geological factors discouraged the boring of such a tunnel. Therefore, the line's engineers decided to construct a 360 degree curve with a radius, rising up from the valley floor, the viaduct forms a part of that curve. The spiral viaduct is long, has a horizontal radius of curvature of , a longitudinal slope of 7 percent, and is made up of nine spans, each in length. The spiral configuration maximises the rate of elevation in comparison to a conventional curve, while also avoiding the inconveniences of a switchback alternative. Wherever reasonable, local materials were sourced for its construction. On 1 July 1908, the viaduct was opened in conjunction with the opening of the

Tirano Tirano ( lmo, Tiràn, german: Thiran) is a town in Valtellina, located in the province of Sondrio in northern Italy. It has 9,053 inhabitants (2016) and is adjacent to the Switzerland-Italy border. The river Adda flows through the town. Main s ...

–

Poschiavo Poschiavo ( it, Poschiavo, lmo, Pusciaaf, german: Puschlav, rm, Puschlav) is a municipality in the Bernina Region in the canton of Grisons in Switzerland. History Poschiavo is first mentioned in 824 as ''in Postclave'' though this comes fro ...

section of the Bernina Railway. In 1943, the whole of the Bernina Railway was taken over by the

; this company continues to both own and operate services across the spiral viaduct to the present day. The services the spiral viaduct carries facilitate not only local trade purposes but tourism as well. Since 2008, the spiral viaduct, along with the rest of the route, has been recognised as a UNESCO

References

Citations

Bibliography

* Belloncle, Patrick. ''Le chemin de fer Rhétique, 1889-1999''. Les Editions du Cabri, Switzerland, , . * Carter, Graeme., Colin Garratt, David Jackson, Howard Johnston, William D. Middleton and Karl Zimmermann. ''Trains: The World's Greatest Trains, Tracks and Travels''. Fog City Press, 2003. . * * Shales, Melissa. ''On the Rails Around the Alps''. Passport Books, 1996. . * Widmer, Markus. ''Eisenbahnbrücken''. Transpress, Stuttgart (Germany), , . * Wolmar, Christian. ''A Short History of Trains''. Dorling Kindersley Ltd, 2019.

External links