Gaag aqueduct consists of a through shaped prestressed concrete structure. The approaches are open concrete structures. The total length is 380 m. The secondary roads along the Gaag river crossing the approaches are constructed as viaducts. The tunnelpart and the approaches are founded on tensile piles because of the high groundwaterlevel. The ship canal is temporary diverted and the aqueduct is constructed in phases. The buildingpits are partly surrounded by steel sheetpiles limiting the effects of the temporary lowering of the groundwaterlevel.