Tradition

Mini guide to Graubünden's bridges

Mini guide to Graubünden's bridges - Tradition

You could call him the father of Swiss bridge building: Christian Menn – resident of Graubünden, construction engineer and bridge builder. Together with his team of engineers, he has planned over 40 bridges in Graubünden alone, and 60 in all. Contura has been to look at some of these impressive constructions.

He's a chip off the old block – or rather bridge: Christian Menn's father Simon also worked in construction. The then 19-year-old began following in his father's footsteps in 1946 when he left his home in Chur to start studying construction engineering at the ETH Zurich. After graduating, he gained professional experience in Chur, Zurich and Bern before deciding to return to the ETH to do a doctorate, which he completed in 1956. After a short spell in a construction company in Paris, he returned to Switzerland to work for an engineering firm in Bern and then, at the age of 30, founded his own engineering company in Chur. In the following 14 years, he and his team of experts designed over 60 bridges, over 40 of them in Graubünden alone. Here is a brief selection.

Sunniberg Bridge, Klosters 1999

It is something of a local landmark: the Sunniberg Bridge, which is part of the Klosters bypass that opened in 2005. It is around 60 metres high, has a span of 140 metres and is 528 metres long. It starts off a few hundred metres below the village of Klosters near Büel and ends at the western entrance to the Gotschna Tunnel, also known as the 'Drostobel'. It thus spans the valley of the River Landquart, which flows by close to the pillars. The Sunniberg Bridge is a cable-stayed bridge – in other words, a bridge whose supporting structure is suspended on cables hung diagonally from pylons. There are four pylons carrying the steel cables on the Sunniberg Bridge. The cables have a load capacity of over 700 tons and consist of parallel wires. Even before it was actually opened, this construction won the international Outstanding Structure Award.

Rhine Bridge, Tamins 1963

The bridge with a span of 100 metres crosses the two tributaries of the Rhine where they meet at Reichenau-Tamins. It is said to be the first arched bridge with a partially prestressed stiffening girder, a major innovation in its time. The bridge has just one narrow, elegant concrete arch, as the box-girder deck and arch form a holistic supporting structure both in terms of statics and construction.

Viamala Bridge, Thusis 1966

The Viamala Bridge is a 180-metre-long road bridge over the approximately 75-metre-deep Viamala Gorge near Thusis – directly at the northern entrance to this spectacular gorge. As the gorge has steep rock slopes on both sides at this point, it would have been very complex and expensive to build supports with sound foundations. That is why Christian Menn wanted to make the leap with a single span: this arched bridge has a span of 86 metres. As was the case with the Rhine Bridge, Menn solved this task by using a slim-line arch and a sturdy stiffening girder.

Cascella and Nanin Bridges, Mesocco 1967

Christian Menn also used the arched concept he had employed in the Rhine Bridge in Tamins for the twin bridges near Mesocco. The two well-known motorway bridges made of prestressed and reinforced concrete are some of the most impressive constructions along the San-Bernardino route, spanning 86 and 112 metres respectively. Coming from the north, cars cross the River Moësa first via the Cascella Bridge to then recross the river on the Nanin Bridge after a 180-degree turn of the motorway.

Langwieser Viaduct

Langwieser Viaduct

Throughout the Swiss canton of Graubünden, it is not just cars but also RhB trains that cross valleys and rivers on impressive bridges. One of these is the Langwieser Viaduct between Chur and Arosa: like a majestic triumphal arch, the single-track railway bridge lies 62 metres above the gorge.