In June 1992 the Norwegian Parliament decided to construct the world’s longest road tunnel. The 24.5km-long stretch of tunnel stretches between Aurland and Laerdal on the new main highway connecting Oslo and Bergen. We decided to take this tunnel twice. So driving 50 km just to see this tunnel 🙂 
The construction was approved to traverse a section of country with relatively poor levels of reliability in road transport due to the mountainous area and narrow roads combined with many fjord crossings.
The Laerdal tunnel is an important part of the extension of a ferry-free, reliable road link between the two largest cities in Norway. The decision to build a tunnel rather than refurbish existing roads was taken to avoid difficult terrain with high risks of rock falls. 
From an environmental perspective, the tunnel was seen as a justifiable investment to avoid destroying sections of the unspoiled natural landscape. The disposal of 2.5 million cubic metres of excavated rock from the tunnel was one of the greatest challenges in planning the tunnel. Shortly before the opening of the tunnel a fan caught fire in a bus carrying about 50 people though the tunnel to the ceremony in Laerdal. The bus filled with smoke, forcing passengers to evacuate while 8 miles inside the mountain. No one was hurt. Passengers reboarded and drove on a few minutes later when smoke dispersed.
Dutch Traveljunk's road to 100 countries 