[1] Most of the line between Oslo and Lillestrøm is through the 14.580-kilometre-long (9.060 mi; 15,945 yd) Romeriksporten tunnel—the second longest railway tunnel in Norway.

The political agreement to build the airport stated that the costs of construction should not be borne by the tax payers.

[2] This company would be able to charge train operators using the railway line; and could use this income to cover its down payments and interest on the debt created to pay for the infrastructure investment.

[3] In 1996 NSB Gardermoen stated that they expected to charge commuter and intercity trains 100 million Norwegian krone per year to use the new line.

Stor-Oslo Lokaltrafikk, which was responsible for buses in Akershus, stated that they had no way to influence NSB's prices, but that they would consider starting a coach service along the route, which would not charge the surcharge.

[8] However, operational speeds in excess of 160 kilometres per hour (99 mph) could not be achieved due to the short distances and limitations on rolling stock.

However, due to limited profitability with the company, from 1 January 2001 the ownership of Gardermobanen was transferred to the Norwegian National Rail Administration, who also owns the rest of railway lines in Norway.

[3] The most challenging part of the construction was the 14,580 metres (47,830 ft) railway tunnel from Etterstad, just east of Oslo S, to Lillestrøm.

[1] Romeriksporten is the second longest railway tunnel in Norway, and is underneath the recreational area Østmarka, in geologically highly unstable ground.

During the construction in 1997, the water level in some of the lakes above the tunnel, including Lutvann and Nordre Puttjern, fell dramatically.

After they were discovered on 3 February 1997 sanctions were initiated by the Norwegian Water Resources and Energy Directorate requiring leakage prevention measures in the tunnel.

An evaluation performed by the Ministry of Transport and Communications showed that NOK 500 million was used on fixing the leaks; however, the report claimed this was, to a large extent, a waste of money due to inefficient engineering procedures.

Full speed utilization of long-distance trains is only possible with the Type 73 units that started operation on the Dovre Line in 2000.

[10][11] The railway is used by both Vy, Flytoget and SJ for their passenger services, as well as freight trains with jet fuel for the airport.

Half of the services make an intermediate stop at Lillestrøm, and continue on past Oslo Central to Asker Station.

[23] This was for some years provided by Linx, a joint venture between SJ and NSB, using modified X2 stock, but the company was later dissolved.

[24] SJ also uses the full line for 5 daily express services to Trondheim Station, these are in form of Type 73 tilting electric multiple units and loco-hauled El 18 trains.

Due to a bridge collapsing, there are fewer direct trains to Trondheim, being in form of Type 76 bi-modal multiple units that take a detour via Røros Station.