When the first train of the day from Poschiavo via the Bernina Pass to St. Moritz reached the plane of Cavaglia at about 6.50 AM, the two pantographs of the Allegra trainset, each fitted with 3 grinding pieces, produced a massive sparks thunderstorm at the 1000 V DC overhead wire. Greenish lightning flashed through the valley and a strong rattling and banging was easy to listen in the distance of about 1 1/2 km. The train moved only very slowly because the main switch fall several times. On the valley floor of the level of Cavaglia in the cold, windless night, a real "lake" of cold air developed (the plane of Cavaglia is sealed by some hills from the valley) and the catenary was isolated by frost and ice.
When the train then 16 minutes later and about 400 m higher, after passing through many curves and loops in a sustained slope of 7.0%, rounded the panoramic curve on the Alp Grüm, no more spark at the pantograph could be seen.
In the background deep in the Poschiavo valley the light traces from cars driving along Lake Poschiavo can be seen.