Have a look at this cool timelapse video of Rijkswaterstaat, how the Dutch build a tunnel under a highway in one weekend.
The new underpass beneath the A12 is inserted into the A12 at the weekend of 20 t / m May 22, 2016. The underpass weighs 3,600 tons and is 70 meters long. Since May 23 the traffic could drive on the A12 towards Arnhem. The third lane in the direction of Arnhem was taken into use.