The Public Roads Administration announced on 10 January 2012 that they intended to build a second tube for the tunnel along with a second carriageway on the section of National Road 23 from the tunnel to the Vassum Interchange on E6 in Frogn. The investment was proposed financed through an extension of the toll collection for an additional twelve to fifteen years. Construction is proposed to start in 2016 and the new tube may be opened in 2019. The project is estimated to cost NOK 2.4 billion.