E4 Bypass Stockholm runs from Kungens Kurva in the south to Häggvik in the north.
When completed, the tunnel system will be the longest motorway tunnel built in Sweden.
As big as the North and South link, Essingeleden, Norrortsleden and Muskötunneln together.
Just over 90 percent of the total rock tunnel has been blasted out and preparatory work is now underway for extensive technical installations.
Follow underground in the video.
Construction can be delayed by four years
The road traffic tunnel was planned to be completed in 2030, but a new ruling from the Land and Environment Court now risks delaying construction.
According to the court's assessment, the tunnels need to be further sealed, and the Swedish Transport Administration is therefore denied permission to increase groundwater discharge when the road tunnels are completed.
The new increased demands for more sealing are estimated to cost between five and nine billion kronor, and delay the start of the bypass until 2034.
The Swedish Transport Administration will appeal the verdict, but does not know if their appeal will be tried.
- This is an important issue for the Swedish Transport Administration, and it is important to consider the far-reaching consequences for the project if the application is rejected.
It will be an increase in cost and a delay in the project, which over the total is not socio-economically reasonable, says Anders Selström, head of department E4 Bypass Stockholm.