The A9 motorway between the interchanges of Holendrecht and Diemen (Gaasperdammerweg) will be widened to 5 lanes in each direction, and a reversible lane. The work on the A9 is part of the Schiphol-Amsterdam-Almere (SAA) road expansion. The road will be placed in a tunnel over a length of three kilometers. Bicycle and pedestrian traffic is routed over the tunnel. The road is sunk into a low hill.

The expansion is necessary to give way to the increasing traffic by road between Schiphol, Amsterdam and Almere. As a result, the air in the residential areas along the tunnel in Amsterdam Southeast will be cleaner and traffic noise will be reduced. A city park will be laid out on the new tunnel roof, and a large number of trees will be planted. The current asphalt barrier between the Bijlmermeer and Gaasperdam will become a green hill.