switzerland, bernina railway, bridge, glacier flow, morteratsch, engadin, pontresina, bernina, meter track, narrow gauge, rhb, rhaetian railways, world heritage, ferrovia retica, graubünden, railroad, alps, tourism, rhätikon, electric locomotive, regional train, clock traffic, all year round, southeast switzerland, abe 8-12, high mountains, bernina pass, svizzera, torrent, glacier water, railroad bridge