Viaduct
A valley bridge is a structure or bridge that spans a valley and simplifies its crossing. Large road bridges and bridges for railways also the viaduct referred.
Railway bridges are called valley bridges in Germany if the bridge deck is more than 14 meters above the terrain.
history
In medieval bridge construction, only low obstacles such as a stream , river or a narrow gorge were overcome in this way . Examples of this are the Teufelsbrücke or the old Lorzentobelbrücke in Switzerland . If there was such a bridge in a valley, the difference in altitude had to be overcome twice to cross the valley.
This was still possible for the horse-drawn carts of that time , but it was exhausting and therefore unsatisfactory. With industrialization and the development by the railroad , the demands on a bridge also changed. The railway z. B. can usually only overcome gradients of up to 30 per thousand (details here ). Road vehicles can cope with inclines of up to 20%, but for the sake of straighter routing and higher driving speeds it makes more sense for motorways and expressways to cross valleys on bridges. Bridges that span an entire valley were in demand and were built using various construction techniques.
This development in bridge construction can be clearly illustrated by the three Lorzentobel bridges in the canton of Zug ( Switzerland ). The Lorzentobel is spanned by an old wooden bridge from 1759, an arched viaduct from 1910 and a modern prestressed concrete bridge from 1985.
The largest viaduct in the world is the Viaduc de Millau, completed in 2004 on the A75 autoroute from Clermont-Ferrand to Pézenas in southern France (list here ). The highest valley bridge in Germany is the Kochertalbrücke on the federal motorway 6 (list here ).
Web links
Individual evidence
- ^ Rolf H. Pfeifer, Tristan M. Mölter: Handbuch Eisenbahnbrücken . DVV Media Group, Hamburg 2008, ISBN 978-3-7771-0378-5 , p. 60