On November 14, 2024, the U-shaped TBM "CREC 1508" passed its FAT in CREG's Xinxiang base, which is going to be used for the infrastructure construction in the Northern Metropolis of Hong Kong. Upon completion, it will be beneficial for improving the flood control capacity in local areas.

This U-shaped TBM is 9.36m wide by 20.72m high, which is independently designed and manufactured by China Railway Engineering Equipment Group Co., Ltd. (CREG). Its design and manufacturing integrate the requirements of the open cut method in the construction of utility tunnels. Combining the advantages of open cut and TBM methods, the U-shaped TBM utilizes the mechanical equipment as a mobile support structure after excavation, allowing for the installation of the main structure of the utility tunnel within the TBM, and making it suitable for the construction of shallow prefabricated utility tunnels.

This project has a total length of 1km with a finished 6.15m (width)×6.35m (height) box culvert cross-section. The geology consists of sandy and silty clay with abundant groundwater, and some sections contain a large amount of silt. To address the high risk and extensive land occupation associated with the traditional open cut method, CREG has combined with the successful application experience of U-shaped TBM in underground utility tunnel projects, and innovatively integrated the TBM with the pipe erecting machine, which can achieve an efficient and integrated construction process for utility tunnels. This process includes transportation, excavation, support, TBM tunnelling, pipe erection and side gap backfilling, which is a new technological breakthrough in the mechanized construction of prefabricated utility tunnels.

Compared with the traditional open cut method, the U-shaped TBM method has higher mechanization, better safety performance and faster construction speed. It requires a smaller construction area, reduces slope excavation and produces less muck and lower noises and vibration, lessening its environmental impact. These advantages make the method safer, faster, more economical, labor-saving and environmentally friendly.