The old rail route through the Gotthardt pass runs in a set of vertical spirals to achieve the vertical elevation. This megalink shows, I hope, a Google Maps 3

The old rail route through the Gotthardt pass runs in a set of vertical spirals to achieve the vertical elevation. This megalink shows, I hope, a Google Maps 3D rendering of the pass and the rail route: https://www.google.co.uk/maps/dir/Schwyz,+Switzerland/Locarno,+Switzerland/@46.4629492,8.8959867,9604a,20y,283.82h,44.95t/data=!3m1!1e3!4m14!4m13!1m5!1m1!1s0x47854d1ba9bd54ed:0xf109e81bad56dc76!2m2!1d8.6529884!2d47.0207138!1m5!1m1!1s0x4785c9fcdf682823:0xff9107992fea3a9a!2m2!1d8.7942643!2d46.1669988!3e3 https://www.google.co.uk/maps/dir/Schwyz,+Switzerland/Locarn... Note that the big loops are inside the mountain.