known as the longest road tunnel ever constructed (24,5 km) , Laerdal Tunnel connects the two biggest cities in Norway, Oslo and Bergen
Design strategies of the project in order to succeed
SINTEF was asked to help design the longest tunnel in the world in western Norway . Experiments were undertaken to evaluate four tunnel models. Results showed that lighting strategies using blue, yellow, and green lights increased driver safety and comfort. A major challenge in constructing long tunnels is reducing driver anxiety, because many drivers feel uncomfortable in this environment. Changes in lighting every 2 km reduced driver anxiety. Including some large openings inside the tunnel also reduced driver anxiety and was useful for emergency operations.
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
Some plans before the construction
These design strategies have proved to be successful with high ratings of driver comfort in the tunnel and no crashes. In addition, the Laerdal project has won two European lighting awards.