The Dovre Line
The whole railway line between Oslo and Trondheim through the Gudbrandsdal valley is called the Dovre Line.
In Dombås it is possible to change to the Rauma Line which can take you to Åndalsnes on the coast and possible to continue by bus to Molde or Ålesund.
The Rauma Line
A train ride from Dombås to Åndalsnes on the coast.
Starting from Dombås (between Oslo and Trondheim) or Åndalsnes, the train takes you through picturesque mountains, over imposing bridges and through tunnels that turn through 180 degrees. On the way down to the bottom of the Romsdal valley, the mountains become higher and wilder, with waterfalls full of glacial meltwater cascading in gushing torrents down the mountain sides. The train passes the tallest rock face in Europe, the Trollveggen, which towers 1,000m (3,281 feet) above the track. The line terminates at Åndalsnes - the alpine town by the fjord. There is a connecting bus service between Åndalsnes and Kristiansund, Ålesund or Molde, from where you can continue your journey on the Coastal Voyage(Hurtigruten).
По железной дороге Осло-Трондхейм до Dombås (это Dovre line), оттуда по Rauma line до Åndalsnes, оттуда автобусом.
По мне так очень геморно, но если вы категорически не летаете...
Вот сайт государственных железных дорог Норвегии:
Норвежские ж/д