Lieråsen Tunnel is a single-tubed railway tunnel of the Drammen Line situated in Asker, Røyken and Lier in Norway. At a length of , the double track tunnel is located immediately between Asker Station and Lier Station. It is used for a mix of short- and long-haul passenger trains and freight trains. Construction of the tunnel commenced in 1962, along with a new section of track between the tunnel and Brakerøya Station. Inadequate geological surveys ahead of construction resulted in the tunnel being built in the middle of an altered and crushed zone, delaying construction and eventually shifting the route to the southwest. The tunnel opened on 3 June 1973. In addition to providing double track, it shortened the Drammen Line by . Part of the old section of the Drammen Line became the Spikkestad Line, while the rest of line was closed. Lieråsen was the longest railway tunnel in the country until the Romerike Tunnel opened in 1999. Specifications The Lieråsen Tunnel is long and carries the double tracked, standard gauge Drammen Line between Asker Station and Lier Station. Running through the mountain of Lieråsen, it passes through the municipalities of Lier, Røyken and Asker. The line is electrified at . At Eriksrud, from Asker Station, there is a switch allowing trains to change track. The tunnel has a surface profile of . The speed is limited to . This is caused by the limited profile, which creates a pressure wave when trains meet, even though the infrastructure and curvature would allow for higher speeds. Starting from the Lier end the tunnel has a slight S-curve with a radius of . History Planning When the Drammen Line opened on 7 October 1872, it was long. This was originally a narrow gauge railway, but it was converted to standard gauge and electrified in 1922. The line was S-shaped between Drammen and Asker, first heading northwards to Lier, where it connected to the Lier Line. It then headed south to Røyken and then northwards again to Asker. The reason for this route was the need to limit the gradient of the line to accompany freight trains. Specifically, there is a steep slope just west of Spikkestad with a height difference of about in comparison to the lower areas below. This height difference forced the line to take the detour. The Lieråsen Tunnel was launched as a project to cut distance and