The opening of the two southern tubes will follow later this year. The fifth tube, the middle tube for the switch track, opens when the connecting project (A9 Badhoevedorp - Holendrecht) is finished. This is expected to be in 2026.
The A9 Holendrecht - Diemen project is being commissioned by Rijkswaterstaat and realised by IXAS, a consortium of Ballast Nedam, Heijmans and Fluor. The project includes the widening of the A9 Gaasperdammerweg, the construction of the Gaasperdammertunnel, the extension of the Holendrecht junction and the construction of two new bridges over the Gaasp river with space for eleven driving lanes. A large park will be built on the roof of the Gaasperdammertunnel, which will connect the districts of Amsterdam Zuidoost. In addition, five park bridges are being built to connect the roof of the tunnel with the surrounding cycling paths.
There is a period of dismantling between the opening of the first and the last tunnel tube. In these months, IXAS will construct a traffic square on the roof of the tunnel to which the Gooiseweg entrances and exits -which are located halfway in the tunnel- will connect. At the end of the year, the route will be completed and all tunnel tubes will be open. Then IXAS will take down the existing A9 and the park will be built on the tunnel roof. The entire project will be completed in 2021. After completion, the consortium is responsible for the management and maintenance of the A9 Gaasperdammerweg until 2038.