travel times between Asker and Drammen, as the Drammen Line was nearly twice the length compared to a straight line. The first proposals were developed by the Norwegian State Railways (NSB) in the early 1940s, albeit at first for a single track. During the process of double tracking the Drammen Line between Asker and Sandvika, NSB launched a proposal to build two additional sections of double track, one from Hokksund to Drammen and one from Brakerøya to Asker. For the latter two main proposals were made: one which would run from the old Lier Station to Asker and a shorter direct tunnel. The advantage of the former was the ability to still serve Lierbyen and smaller construction costs, while the latter would give a shorter overall line length. NSB called for prioritizing the Drammen–Hokksund segment if there was not funding for both. Construction Construction involved building a new at-grade line from Brakerøya Station to a new Lier Station and subsequently a new tunnel through Lieråsen to Asker. Lieråsen is a granite massif and was regarded to be simple area to work in. The planning was carried out with limited geological surveys. Construction started in 1963, but it was soon discovered that there were long altered zones running through the area where the tunnel was to run. Specifically, a long crushed zone was located there. After two years the route was therefore shifted about to the southeast to avoid these zones. This resulted in a slight S-curve on the Lier end. Construction continued slowly, as nearly the entire length of the tunnel needed to be reinforced with concrete. By 1966 the cost estimate for the tunnel reached NOK 454 million, up from 64 million in 1959. Break-through of the main tunnel took place in October 1971. The price ended at NOK 175 million and construction employed up to 250 people on the site. Two workers were killed and two seriously wounded due to a blasting accident on 23 June 1972. The opening of the tunnel on 3 June 1973 resulted in a shortening of the Drammen Line by , cutting the distance from Drammen Station to the then terminus of Oslo West Station to . Travel time from Drammen to Oslo was also cut, from between 55 and 50 minutes to 30. This allowed for the new Class 69 commuter trains to be put into service on the Drammen Line. The