Subterra's project (SBT Sverige) includes two 2 x 4 km road tunnels on the new Stockholm ring road, along with 4.3 km of ramps. Some of the tunnels go under Lake Mälaren – we even had the chance to walk there, 60 meters below the ground!

When it's finished, the E4 Stockholm Bypass (Förbifart Stockholm), a new European highway around Stockholm, will link the southern and northern parts of Stockholm County. This will make city traffic better and reduce congestion in the Stockholm traffic system.