"Stammnetzallegra" or STZ (Stammnetztriebzug) ABe 4/16 # 3105 of the Rhaetian Railway is crossing the 284 meter long and 62 meter high Langwieser viaduct, on the Arosa line between Litzirüti and Langwies, with the village of Peist in the background. Operation of this train type is rather new on this line with steady grades of 6.0 %. Usually there are the "Allegra" ABe 8/12 (ZTZ Zweispannungs Triebzug) operating on this line, which have the double power and can pull up to 4 cars. On the opposite valley slope, you can see the railway line going from Langwies towards Peist and finally Chur. The Langwieser viaduct was built in 1913/1914 for the then independent Chur-Arosa Bahn (ChA), which was taken over by the Rhaetian Railway in 1942. The line was electrified since the opening in 1914 with 2400 V DC, but was changed to 11000 V 16,7 Hz AC in 1997 (now the same as the RhB main network).