On January 6, 2024, the Herrenknecht Mixshield (diameter 15.71 meters) broke through to the target shaft, completing its drive for the left line of the Jinan Jiluo Road North Extension Tunnel near Jinan. The machine for the parallel right line followed on February 29.

In each of these 2 kilometer long large-diameter tunnels a three-lane road tunnel will be built with a railway line underneath.

Mechanized tunnelling faced challenges of low overburden, tunnelling close to buildings’ foundations, high water pressure and complex geological conditions consisting of mainly clay and silty clay layers containing calcareous nodules locally. In particular, the machines had to pass under the Queshan Reservoir, the main water source of Jinan City.

Before successfully completing the North Extension Tunnel, the two XXL machines had been employed for the 2.5 kilometer long Jinan Jiluo Road Yellow River Crossing Tunnel.