Spiralen (Drammen)( Drammen Spiral )
The Drammen Spiral (Norwegian : Spiralen Drammen) is a tunnel near Drammen, Norway.
Drammen city ground conditions are poor, with most buildings being founded on clay. Gravel was obtained from a quarry, but by the 1950s concern was raised that quarrying was beginning to disfigure the local landscape. Eivind Olsen was the City Engineer at the time, and he proposed the idea of tunnelling for gravel. Olsen came to be nicknamed 'Father of the Spiral Tunnel'. The community decided to tunnel for stone as an alternative to quarrying, creating a tourist attraction as a by-product. Construction started in 1953 upon closure of the quarries. Rock excavated for the tunnel was crushed and used to make a harbour embankment in the city, while stone was used in concrete. The rock is a type of granite named after the city: Drammensgranitt (Drammen granite). The tunnel was opened for traffic in 1961 by King Olav V.
From October 2019 the tunnel went through extensive renovation and was closed for months. Refurbishment included numerous structural and safety improvements as well as adding coloured lighting to make the tunnel an even bigger tourist attraction. The lighting changes according to the time of day. The work cost around 10 million euros and the tunnel was officially reopened on Dec 12 2020. The tunnel is owned and operated by the Drammen Kommune (municipal administration).