Chongqing is one of the largest cities in China. However, the water supply structure often reaches its limit. In order to sustain the main urban area the city decided to build the new Guanjingkou reservoir.

Along the alignment, four Herrenknecht AVN machines drove more than 16 km of tunnels with a single drive length of up to 1,702m and overburdens of up to 325m. The challenging tunnelling was only feasible with a special machine design.

All four machines were delivered with a retractable mechanism. Therefore they could bore towards each other, and after they reached the final position, the shields could be dismantled inside the tunnel and the main machines could be relocated back to the launch shaft – ready for the next mission and saving several reception shafts