Indeed, if we assume cyclists use the tunnel 100 days a year going both ways through it, thats saving each one nearly 60+ hours a year. If each one's time is worth $20, that is over a thousand dollars per cyclist per year - it only takes 9k cyclists to make the savings outweigh the costs in five years.
And assuming that this will increase the number of people who choose to bike instead of to drive, you can also add savings for all the remaining drivers who get a slightly easier commute.
Why only 100d/y while Norwegian works around 190d/y? In my experience people tends to have a “main” commute mode that they only turn away from in exceptional cases. Easier to live with habits that mixing your timetables every other day.
People might use cars or public transport instead of a bike to commute if there is heavy rain or snow. This is an important consideration in Bergen which is notoriously the rainiest city in Europe (it rains more than half the time).
That's averages over the whole countries though - the north and west of the UK (particularly the Scottish Highlands and the Lake District) are a lot wetter than the south-east where London is.
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).
Not just a raincoat, I've had snow, sunny summer, storm gusts, hail and rain on the same day just this week, I'm int he SW though not entirely west.
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!
One of the factors other replies haven't considered is that Norway routinely spends a lot on transport infrastructure, with cost-benefit just one of the factors. This project was relatively cheap compared to the constant building of tunnels for cars that happens across the country. A typical project costs many times more than this.
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.
Okay. Taking the 20min saved per ride from the article, and 300 rides that would otherwise take the longer route per day out of my ass, we get 100 hours saved per day. That's approximately 4 days saved per day.