Razel-Bec helped construct the Grand Paris Express line 15 south tunnel. The 9.80 m diameter tunnel was excavated with two tunnel boring machines, Camille and Aicha, over a total length of 7.2 km. The project’s special feature was the geological diversity of the route: the TBM passed through a sedimentary series of the Paris Basin, then through Campanian chalk at its deepest level to supragypseous marl.