The Glacier Express

S1, E1: Connecting iconic mountain resorts St Moritz and Zermatt, the Glacier Express is filmed from above winding along alpine peaks, over treacherous gorges and through vertiginous mountain ranges.  It’s a constant struggle to keep on track as engineers battle deep snow drifts, harness the latest tech to protect the line from landslides and set explosives to guard against deadly avalanches.