"Allegra" ABe 8/12 # 3503 of the Rhaetian Railway is crossing the 145 meter long and 46 meter high Gründjitobel viaduct between Peist and Langwies, on the line from Chur to Arosa, with train R 1437. This is a push pull train with a mixed first/second class standard car type II, a second class standard car type I in the "Bärenland" paint scheme and a cab car BDt. In the very rear is a loaded gravel car Fad of the ARGE Frischbetonwerk Arosa. The load is near the maximum for the "Allegra" on this line with steady grades of 6.0 % and narrow curves with a radius of 52 meter. The maximum velocity on this line is 35 km/h only. The impressive viaduct leads the railway line over the Gründjitobel, a steeply eroded gravel moraine gorge, with sandy formations known as "Steimannli". The main span consists of an arch with an 85 metres (279 ft) long span, and a rise of 46 metres (148 ft) above the valley floor.
The whole build of the structure proceeded virtually trouble free, and could be completed in just one year. Together with the larger Langwieser Viaduct, which can be considered its prototype, the Gründjitobel Viaduct was, as at the date of its completion, one of the longest spanning railway bridges in the world. The falsework, which had already been used in the construction of the Halen Bridge in Kirchlindach, Bern, originated, as with the Langwieser Viaduct, from Richard Coray of Trin. The structure was built by the firm Müller, Zeerleder und Gobat in 1913/1914 for the then independent Chur-Arosa Bahn (ChA), which was taken over by the Rhaetian Railway in 1942. Till 1997, the line was electrified since the opening in 1914 with 2400 V DC, then it was changed to 11000 V 16,7 Hz AC like the main network of the RhB.
