Construction start for 900-meter submarine tunnel under Shizimen channel. Outer tunnel diameter 7.7 meter. Inner diameter 7 meter. China Railway Construction Heavy Industry has designed and produced special Earth Pressure Balance EPB Tunnel Boring Machine in in Changsha, Hunan. Diameter of EPB TBM is 7.98 metre.

https://www.macaubusiness.com/lrt-extension-to-hengqin-initiates-tunnel-boring-works/