The Lærdal Tunnel () is a road tunnel connecting Lærdal Municipality and Aurland Municipality in Vestland county, Norway; the southwest end of the tunnel is approximately northeast of Bergen. It carries two lanes of the European Route E16 highway, and was the final link completing the main highway that now enables car travel between Oslo and Bergen with no ferry connections and no difficult mountain crossings during winter. It is the longest road tunnel in the world, followed by Tianshan Shengli Tunnel in Xinjiang, China and WestConnex in Sydney, Australia.
History
In 1975, the Parliament of Norway decided that the main road between Oslo and Bergen would run via Filefjell. In 1992, Parliament confirmed that decision, added that the road should run through a tunnel between Lærdal Municipality and Aurland Municipality, and passed legislation to build the tunnel. Construction started in 1995 and the tunnel opened on 27 November 2000. It cost 1.082 billion Norwegian kroner ($113.1M USD).
Beginning in September 2026 the tunnel will be completely closed for 12 hours each night from 18:00 - 06:00 for two years, to meet changes to EU safety regulations. Alternative routes such as road 50 are available, but are slower and often closed in winter.
Design
A total of of rock was removed from the tunnel during its construction from 1995 to 2000. The tunnel begins just east of Aurlandsvangen in Aurland Municipality, goes under a mountain range, and ends south of Lærdalsøyri in Lærdal Municipality. Its design takes into consideration the mental strain of driving through a long tunnel; it is divided into four sections, separated by three large mountain caves (with parking areas available) at intervals. While the main parts of the tunnel have white lights, the caves are lit in blue with yellow at the fringes to give an impression of sunrise. These caves are meant to break the monotony, providing a refreshing view and allowing drivers some relief. They also function as turnaround points, and as break areas to help alleviate claustrophobia during the 20-minute drive through the tunnel. Speed cameras have been installed <!-- around 2005-2010 ? --> because of serious speeding. There are very few other completely straight roads in the region.
Air quality
Air quality in the tunnel is managed in two ways: ventilation and purification. The Lærdal Tunnel is the first in the world to be equipped with an air treatment plant, located in a -wide cavern about northwest of Aurlandsvangen. Air from the tunnel is drawn into the plant by two large fans, particulates (dust and soot) are removed by an electrostatic filter, and nitrogen dioxide is removed by a large carbon filter.