It's the escape tunnel for a tram tunnel with an extra coat of paint: https://www.lifeinnorway.net/bergen-cycle-tunnel/
$46M USD, to save cyclists 5.5km/20 minutes; that seems like a pretty good return.
https://en.wikipedia.org/wiki/List_of_countries_by_average_a...
Also, "volume of rain" might be misleading because it doesn't give you a feeling for how often it rains. The Highlands in particular can have a light rain that falls for weeks at a time (or at least seems like it if you are in a tent).
I remember one time a few years back when I lived in Stavanger, I went to the post office in the city center there in a bright nice summer day and came out to torrential rain and rivers in the street!
Plus the saving in car TCO and fuel, plus less road maintenance.
From https://www.fhi.no/en/op/hin/population/life-expectancy/, life expectancy in Norway is about 82 years.
Together, that means the tunnel will save one human life in about 20 years, not taking into account pedestrians, or indeed realistic usage numbers.
That obviously depends on a lot of parameters, not least how many cyclists are impacted and how often.
Per capita Norway is one of the highest spenders in the world, due to the size and low population density of the country. Even with all this spending, transport in some places, especially the north, is slow & inefficient. This has resulted in a high number of airports and Norwegians flying more than almost every other nationality.
In this case it is too expensive/unpractical as you would have to dig several hundred meters up a mountain. Also a tunnel going sideways is easier for those who can not walk. And this long stairs up could be a problem even to those who can walk.
For those who don’t know the tunnels goes through a 477m high mountain/hill and both ends are roughly at sea level.
Older tunnels the "walk away from the dead train" option was heavily used; but more often now they try to deal with "get away from the horribly burning dead train that will suffocate everyone".