Trunk Line
NSB made four proposals for a new railway to Gardermoen. The simplest devised constructing a branch from the Trunk Line at a location north of Jessheim Station which would run to the airport. Alternatively, and ultimately selected, was construction of a tunnel eastwards from Oslo to Lillestrøm and an upgrade of the Trunk Line and a new route from a point at Asper to the airport. Two more direct routes were proposed; the one branching off from north of Grefsen Station on the Gjøvik Line, the other diverting from the Trunk Line close to Grorud Station. All four routes called for the railway to continue north from Gardermoen and meet up with the Trunk Line at Bøn Station.