The line opened on 10 October 1934 as a light rail. In 1993, it was upgraded to metro standard as the first light rail west of Oslo, with two stations being closed. The Ring Line opened in 2003. Forskningsparken has transfer to the Oslo Tramway and serves Rikshospitalet. Forskningsparken and Blindern both serve the University of Oslo, while Ullevål stadion serves Norway's largest football venue. North of there the line mainly serves residential areas. Sognsvann serves the Norwegian School of Sport Sciences and the recreational area Nordmarka.