Former Furka-Oberalp Bahn (now DFB) cogwheel steamlocomotive HG 3/4 # 4 with her train is crossing the Steffenbach bridge. The special construction of this bridge allows to withdraw it on the abutment respectively to flip down during the winter months to allow the free path for avalanches. Explanations in German here:
http://www.mfb-basel.ch/steffenbach.htm