The city council voted in favor of building the Ring Line on 25 June 1997, against the votes of the Progress Party. Financing was partially ensured in December, when a political agreement was reached for Oslo Package 2, a financing plan for investments in public transport in Oslo and Akershus between 2002 and 2011. Construction started in June, with the Agency for Road and Transport of the municipality responsible for construction. The first section opened from Ullevål stadion via Nydalen to Storo on 20 August 2003. With the opening, Line 4 was extended from Ullevål stadion to Storo. On 20 August 2006, the final section opened, from Storo via Sinsen to Carl Berners plass.