Brussels Metro is a rapid transit system that serves a large portion of the Brussels, Capital Region of Belgium. It consists of 4 conventional metro lines and 3 pre-metro lines.

Line 3 is a tram line that runs through the city center from Churchill in the south to Esplanade in the north, using the North-South Axis tunnel. The total route will be 10.3km long.

An 150m long new tunnel was dug underneath the Brussels North railway station to connect two existing underground tunnels. It was an important component of the new metro link.

Dextra supplied Sonitec, a tube solution that facilitates the integrity testing of foundations using the CSL testing method, to the construction site of Line 3. 13 kilometers of the tubes were installed in the 18m long pile cages.

The Sonitec system has been designed with the sole purpose of being easy to assemble and install in reinforcement cages.