Steffenbach Bridge
The Steffenbachbrücke (also Steffenbach tobel bridge ) is a railway bridge on the Furka mountain route . The steel bridge built in 1925 has a span of around 36 meters and a maximum height of around 17 meters. It is remarkable because it has to be dismantled every autumn and reassembled in spring to protect it from avalanches .
The bridge is located in the north-eastern, Uri part of the route between Realp and Tiefenbach at 1765 m above sea level. M.
history
The stone viaduct , built on this site between 1912 and 1914 , was destroyed by an avalanche in May 1916, before a train ever passed over it. The First World War delayed the reconstruction of the bridge and the further construction of the line. It was not until 1925 that the bridge construction company Theodor Bell & Cie. the new bridge was completed, which could be kept out of the way of the avalanches following the Steffenbachtobel by a folding construction. The interruption of the rails was not a problem because the route was not winter-proof anyway. The idea of this bridge construction came from the chief engineer of the Rhaetian Railway Erminio Bernasconi.
construction
The bridge girder consists of three parts and, like the adjoining sections of the route, is arranged with a gradient of 110 ‰. The two connecting points are supported by inclined pendulum supports on the foundations of the brick-built bridgeheads that are inclined outwards. The construction weighs 32 t, plus 15 t for the track superstructure with rack .
Assembly and disassembly
For dismantling, the approx. 13 meter long middle part of the girder is lowered so that one end hangs on the bridge girder on the valley side. The two outer girders, each approx. 11.5 meters long, are then lifted at the abutment and pulled outwards over the adjacent sections of track until the pendulum supports attached to them rest on the bridge heads. This is done from above (Tiefenbach side), with the ends of the support parts each hanging on a pulley and being lifted or moved by coordinated operation of the cable winches. In this "winter position", the central part of the bridge that hangs down rests on the support on the valley side and in this position is protected from avalanches by a protruding wall.
The reconstruction takes place in reverse order. It is not uncommon for a part of the snow lying under the bridge to be removed beforehand so that the hanging center piece in particular can swing freely.
No crane is required for assembly and dismantling. Two winches are sufficient, the two assembly stands, which are permanently mounted (also during the pulling operation) above the abutments, a movable auxiliary stand and some pulleys and pulleys, which are stored in a small shelter near the bridge. The winches were originally operated by hand. Today electric motors make work easier, so that assembly and dismantling can be done in one day.
literature
- Peter Fessler: The Steffenbach Bridge . In: Journal of the Association of German Engineers . tape 77 , no. 13 . Munich April 1, 1933, p. 356–357 ( copy [accessed on April 2, 2018] with a diagram of the bridge showing the dismantling and construction).
Web links
- DFB: data and pictures , etc. a. also with photo documentation of the dismantling and avalanche clearance work
- Steffenbachbrücke after an avalanche
- Video of the construction of the bridge
Coordinates: 46 ° 35 ′ 4.9 " N , 8 ° 28 ′ 32.3" E