Solis Viaduct

The Solis Viaduct (Soliser Viadukt) is a single track eleven-arched limestone railway viaduct. It spans the Albula east of the hamlet of Solis, in the canton of Graubünden, Switzerland.

Designed by the engineer Hans Studer, it was built in 1902 by Munari, Cayre und Marasi for the Rhaetian Railway, which still owns and uses it today. One of the most important structures on the World Heritage-listed Albula Railway, it is 89 m high, 164 m long, and has a main span of 42 m.

Location
The Solis Viaduct forms part of the Albula Railway section between Thusis and Tiefencastel, and is at the 49.33 km mark from Thusis. East of the viaduct is the Stausee Solis.

Description
The limestone-built viaduct was conceived by Hans Studer as the first stone arch bridge in Switzerland to be designed in accordance with the elasticity theory. That choice of design allowed the use of a parabolic arch, and thus a very slim form of construction. Building costs could thereby be limited to 125,000 Swiss francs at 1902 prices.

With its height of 89 m, the Solis Viaduct is the highest on the Rhaetian Railway. It consists of a main span of 42 m flanked by 10 other spans ranging from 8 m to 10 m.

Renovation
In 1997, the viaduct was renovated at great expense. The previous isolation between the gravel bed and walls was filled in by a new sealing system, incorporating liquid plastic film and shotcrete. In addition, the rails and ballast were renewed.