Work on the overall Emscher conversion project began back in 1992, covering more than 400 kilometers of new underground sewer tunnels. The inhomogeneous ground, the pipe position in up to 40 meter depth, the long pipe jacking distances, the partially complex logistics and the wide range of different construction situations posed particular challenges in the creation of the necessary tunnel structures. Over almost 25 years the contractors relied on Herrenknecht's project-specific tunnelling technology for the underground excavation work in construction sections 20, 30 and 40. This included numerous AVN machines for pipe jacking in the smaller diameter range, EPB Shields using the pipe jacking and segmental lining methods as well as a Vertical Shaft Sinking Machine or VSM to sink a 23 meter deep launch shaft. Over 60 kilometers of the main and secondary sections were built by contractors using Herrenknecht tunnelling technology. In individual construction phases, Herrenknecht Group partners supported the quick overall construction process. VMT supplied TBM navigation systems as well as various communication, data management and safety systems. Herrenknecht Formwork produced segment moulds and MSD supplied rolling stock, a lifting beam and a tilting table for the pipe plant in Gelsenkirchen.