The Steffenbach Bridge is a railroad bridge on the Furka mountain line. Built in 1925, the steel bridge 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 fall and rebuilt in the spring to protect it from avalanches. On this day, the bridge was being rebuilt for the summer season, and the auxiliary trestle for its assembly can still be seen on the bridge. From Wikipedia: Assembly and disassembly:
To dismantle the bridge, the approx. 13-metre-long middle girder section is first lowered down so that one end hangs from the bridge girder on the valley side. Then the two outer girders, each approx. 11.5 meters long, are lifted at the abutment and pulled outwards over the adjoining track sections until the pendulum supports attached to them rest against the bridge heads. This is done from above (Tiefenbach side), whereby the ends of the girder sections are each suspended from a pulley block and lifted or moved by coordinated operation of the cable winches. In this "winter position", the suspended middle section of the bridge rests on the support on the valley side and is protected from avalanches in this position by a wall projection.
Reconstruction is carried out in reverse order. It is not uncommon for some of the snow under the bridge to have to be removed first so that the suspended middle section in particular can swing freely.
No crane is required for assembly and dismantling. All that is needed are two cable winches, the two assembly trestles, which are permanently mounted above the abutments (i.e. also during train operation), a movable auxiliary trestle and a few pulleys and pulley blocks, which are stored in a small shelter near the bridge. The winches were originally operated by hand. Today, electric motors make the work easier so that assembly and dismantling can be completed in one day. A picture of the bridge in the winter position: https://www.railpictures.net/photo/616487/
