Following the 1991 decision to build a new Rikshospitalet at Gaustad, it was decided to extend the Ullevål Hageby Line of the tramway there, which would pass under the Sognsvann Line. Plans called for a transfer station at Blindern, but this was later discarded in favor of a new station, Forskningsparken. It would replace Vestgrensa, which was considered too far away to be a suitable transfer point. Forskningsparken would also serve the northern part of the Blindern campus. Not until 1998 were the necessary political agreements in place to allow construction to start. The new light rail started services on 1 June 1999, and the rapid transit station opened on 22 August. With the opening, Line 4 of the metro was extended from Blindern, via Forskningsparken, to Ullevål stadion. There were complaints from local residents that the increased traffic on the line was causing too much noise, and neighbors demanded that noise shields be built.