The tunnel through the Brunkeberg ridge is a shortcut I seldom take, but I took it today. It’s 231 metres long, 4 metres wide and 3.9 metres high and was opened in 1886 by King Oscar II. Explosives could be used from the east side, but its west side displayed all the problems a boulder-ridge can cause because of the pebbles and sand. The problems were not only of the technical kind; the constructor, engineer Knut Lindmark, also got in financial troubles because of this.
The solution he used was indeed very much ahead of its time – he rented refrigerating machinery from England and froze the ground to -18 degrees (centigrades). After that, all the cut away works could be carried out safely. Using the tunnel is free of charge today, but people who wanted to use it when it was opened had to pay a fee of 2 öre.