The famous Flam railway runs all year and links to the main Bergen - Oslo line
The Flåm railway runs all year,
not just during the summer

Buses and trains in Norway

Railway services:

There are long-distance express train services from Oslo to Bergen, Oslo to Kristiansand, Oslo to Trondheim and Bødø, Stavanger to Kristiansand (and on to Oslo), and others, including the line down to Gothenberg in Sweden.

There are also local and regional rail services.

This is a country where lakes, mountains, the sea, and weather all conspire to make good communications difficult, but the train service does its best.

Bus and coach services:

There are extensive regular bus services within the cities and towns.

There is also a network of long-distance coach services that connect the towns, for example Kystbussen runs between Stavanger and Bergen - often stopping at Haugesund, and linking with Ryanair flights. 

There are airport bus services and also skibuss services