The airport is connected to the city center by the high-speed railway Gardermoen Line served by mainline trains and Flytoget. The percentage of passengers using public transport to get to and from the airport is one of the highest in the world at nearly 70%. The ground facilities are owned by Oslo Lufthavn AS, a subsidiary of the state-owned Avinor. Also at the premises is Gardermoen Air Station, operated by the Royal Norwegian Air Force. An expansion with a new terminal building and a third pier opened in late April 2017.nnThe airport location was first used by the Norwegian Army from 1940, with the first military airport facilities being built during the 1940s. The airport remained a secondary reserve and airport for chartered flights to Oslo Airport, Fornebu, until 8 October 1998, when the latter was closed and an all-new Oslo Airport opened at Gardermoen, costing 11.4 billion Norwegian kroner (NOK)
