Brusio spiral viaduct

Geschichte

The Brusio spiral viaduct is a single-track nine-arched stone spiral railway viaduct.A signature structure of the World Heritage-listed Bernina railway, it is located near Brusio, in the Canton of Graubünden, Switzerland, and was built to limit the railway's gradient at that location within its specified maximum of 7%.LocationThe Brusio spiral viaduct forms part of the Bernina Railway section between Brusio and Campascio. It is just south of Brusio, and approximately from St. Moritz.HistoryThe viaduct was opened on 1 July 1908, upon the opening of the Tirano–Poschiavo section of the Bernina Railway.A spiral viaduct was required immediately south of Brusio to limit the railway's grade to the required maximum of 7%, so the train would not slip on the way up, or be uncontrollable on the way down. Geological factors prevented the boring of the spiral tunnel that had originally been planned. Engineers therefore decided to construct on the valley floor a 360 degree curve with a 50to radius, and the viaduct forms part of that curve.