You can also travel by bus in Norway. It took me some time to find a website for timetables, and more information. Because lesser and lesser Norwegians travel by bus, the frequency of departures and arrivals is decreasing. The timetables change often, and it needs a constant updating for the right information.
Bus travel is relatively expensive: it costs almost the same as train travel on a similar distance. You pay the driver. They all speak English, or understand English.
Be aware of the time to go back, check the timetable about the last possibility to return. Finally only an expensive taxi can bring you home.
Be aware of typing the Norwegian names with special characters like the Å of Ål. When using only the normal A it creates Al, the Norwegian website cannot read that, so it will not be found. Eventually you copy this name from somewhere on internet and paste it there.