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.

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.