Guangdong's first ultra-long pipe-jacking submarine utility tunnel was connected on Nov 25, two months ahead of schedule, according to China Southern Power Grid's Zhuhai Power Supply Bureau.

The section across the Maliuzhou Waterway is the most complicated and challenging part of the 3rd Macao-Bound Power Transmission Channel. The working shaft had to stretch 1,022 m (1,118 yd) 28 m (31yd) underground to create a utility tunnel with an outer diameter of 2.64 m (3 yd).

In addition to a 1,600-ton-thrust by the jack dynamic system, many advanced technologies and much equipment were applied in the pipe-jacking process to avoid subsidence and skewing. They include GPS positioning, auto-mapping by total station, and reexamination by laser theodolite.

Construction site [File photo]

The utility tunnel, featuring compact land use, can abate the impact of natural forces such as typhoons on the stable operation of power grids, and lower damage caused by external forces on electrical equipment.

Construction of the 3rd Macao-Bound Power Transmission Channel, also known as the 220-kilovolt double-circuit power cable project from Zhuhai's Yandun Station to Macao's Bei'an Station, commenced in late February.

When operational in late June, the channel will serve as a midway power transmission line to boost the current southern and northern ones, increasing power supply to Macao from 1 million kilowatts to 1.7 million kilowatts.

Meanwhile, a new pattern, consisting of 220-kilovolt eight-circuit and in-reserve 110-kilovolt four-circuit lines, will take form to increase the stability of power transmissions.