In addition to providing double track, it shortened the Drammen Line by 12.4 kilometers (7.7 mi).

[1] At Eriksrud, 10.48 kilometers (6.51 mi) from Asker Station, there is a switch allowing trains to change track.

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.

Specifically, there is a steep slope just west of Spikkestad with a height difference of about 100 meters (330 ft) in comparison to the lower areas below.

[1] The first proposals were developed by the Norwegian State Railways (NSB) in the early 1940s, albeit at first for a single track.

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.

[1] Construction continued slowly, as nearly the entire length of the tunnel needed to be reinforced with concrete.

[14] Part of the financing of the tunnel was channeled from a surcharge which NSB imposed on all tickets running through Lieråsen.

[18] A short-coming in the tunnel's design was the lack of any lighting, emergency exits or water deviation.

Poor geological conditions resulted in a net being hung up over the rails to hinder rocks from falling down.

[22] The National Rail Administration and the government are working on plans for a future high-speed railway which would include upgrading the Vestfold Line to 250 kilometers per hour (160 mph).

There are no plans for upgrades between Drammen and Oslo, which would make the Lieråsen Tunnel a bottleneck in the new system.