same architectural style. They are constructed in concrete with steel columns and wooden sheds and fences. All platforms have a shed; Ullevål stadion has a larger weather cover and has a design inspired by football. The upgrade also included the installation of third-rail from Majorstuen to Stortinget in the Common Tunnel. From 10 January 1993, the Sognsvann Line re-open, and from 4 April, the line started operating through the Common Tunnel and connected to the Lambertseter Line. The new service became operated with T1000 rolling stock. 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. In 1991, Oslo Sporveier presented plans to connect the Sognsvann Line to the Grorud Line with a new Ring Line. The company also considered building the ring as part of the tramway, and have combined operation with both tram and metro on the Sognsvann Line. This was later discarded, despite the higher investment costs with a metro, since the tramway would give higher operating costs and longer travel time. A detailed suggestion was presented by Oslo Sporveier in August 1996. It became clear that Berg would not be served by the Ring Line. Many neighbors to the Sognsvann Line complained about the proposal, stating that they had hoped that the section from Majorstuen to Berg would have been rebuilt as a tunnel. They also argued that it was irrational that the line was running at-grade in densely populated areas, while it would run in a tunnel through the then mostly unpopulated Nydalen. To compensate, Oslo Sporveier stated that they