sentences:  Any further increase in capacity would only be possible by building a second tunnel through the city center.The first plans called for a tunnel further north, roughly halfway between the Common Tunnel and the Ring Line, possibly in addition to a new tunnel through the city center.Plans from 2011 have called for a new tunnel which runs from Majorstuen via Stortinget to Tøyen, but following a different route and with intermediate stations at Bislett, Hammersborg and Olaf Ryes plass, in the St. Hanshaugen and Grünerløkka boroughs north of the city center.