Maybe the disc cutters were not Herrenknecht. You know how it works. First x meters you use disc cutters of the TBM manufacturer. So maybe first x meter they used Herrenknecht disc cutters and then switched to an after...
pretty imressive. I heard that it hasn't been a smooth ride all along. I heard they had to change a lot of disc cutters along the way. Like I heard 20 disc cutter every single day had to be replaced!