A tunnel is actually a large cabinet you build around an installation. That is certainly true of the extension of the A4 motorway between Delft and Schiedam; the route has been there for years and the tunnel was built over it.
Last December I worked as a support employee in the PROCENTEC test team carrying out the network audit on this very special network. The stretch of motorway is actually 7 km long: 1 km at ground level, 2.6 km half-sunken, 1.4 km sunken and a land tunnel extending for 2 km. This resulted in an incredibly long PROFIBUS network where we had no less than 190 segments to check.