In February 2026, a special "surgery" is about to begin on the banks of the Karnaphuli River in Chittagong, Bangladesh. The giant shield machine with a diameter of 12.12 meters from China is about to penetrate deep into the riverbed and embark on its overseas journey. Local residents gathered on the shore, curiously observing the "steel dragon" that was about to change their lives. No one can imagine how this equipment from China will rewrite the infrastructure map of this country.

Six years later, in October 2023, when the first car drove through the riverbed tunnel, the journey that would have taken several hours to detour on both sides was shortened to a few minutes. This 9.3-kilometer-long Karnaphuli River Tunnel not only connects the east and west banks of Chittagong City, but also connects China's high-end equipment with the world stage.

Steel Dragon, China's Intelligent Manufacturing

This historic shield tunneling machine was developed by CCCC Tianhe, a subsidiary of China Communications Construction Corporation. The cutterhead diameter is 12.12 meters, the length is 94 meters, and the weight is over 2200 tons. Its mission is to connect the 2450 meter shield tunnel section at the bottom of the Karnaphuli River, which is a key part of the dual tunnel four lane tunnel with a designed speed of 80 kilometers per hour.

As China's first ultra large diameter shield tunneling machine to go abroad, its birth itself signifies a breakthrough. For a long time, the market for ultra large diameter shield tunneling machines has been monopolized by developed countries. In order for China's equipment to enter this field, it must demonstrate its true capabilities.

In response to the complex fine sand geology at the bottom of the Karnaphuli River, the R&D team has developed a series of self created technologies: the cutterhead anti caking mud cake design prevents excavation from being "stuck" by clay; The layered backwashing technology of the mud water system ensures stable propulsion even in sand layers; Intelligent anti settlement control technology protects riverbeds and ground buildings; The automatic control of the mud water circulation system makes the operation more precise. These technologies effectively solve world-class construction problems such as sand liquefaction and cutterhead mud cake formation.

Overcoming difficulties and creating miracles

After the project started in December 2017, this "steel dragon" began its journey in a foreign land. The geological conditions at the bottom of the Karnaphuli River are extremely complex, with fine sand formations resembling quicksand. A slight mistake can lead to landslides or equipment jamming. But Chinese shield tunneling machines speak with their strength - in construction and excavation, they have achieved good results with the fastest daily excavation of 10 rings (2 meters per ring) and monthly excavation of 171 rings, which has impressed foreign counterparts.

This is not only a competition of speed, but also a competition of technology. In the past three years of excavation, the shield machine has steadily crossed multiple geological fault zones at the bottom of the river, successfully dealing with the risk of sand liquefaction without any safety accidents. In October 2023, the tunnel was officially opened, giving birth to the first riverbed tunnel in the history of Bangladesh.

Glory, the pearl of the the Belt and Road

The significance of this tunnel goes far beyond convenient transportation. As an important node project of the Bangladesh China India Myanmar Economic Corridor, it has revitalized the port city of Chittagong, connecting the previously fragmented economies of the two sides. More importantly, it witnessed the journey of China's high-end equipment going global.

The honors this shield tunneling machine has received confirm its extraordinary status: first prize in the Science and Technology Progress Award of China Communications Construction Corporation, first prize in the Science and Technology Progress Award of China Construction Enterprise Management Association, gold medal in the Product Design Group of Jiangsu Province's "Governor's Cup" Industrial Design Competition, and was also selected as one of the "Top Ten Engineering Scrolls of Xinhua News Agency". Keywords: Southeast Asian Engineering Information Network, Overseas Engineering Construction

Looking back now, the Bangladeshi boy standing by the river in 2017 may have already driven his car through this underwater tunnel to work on the other side. The Chinese shield tunneling machine that changed his life has completed its mission and lies quietly in the archives of history. But the journey it started is far from over - by 2025, China's super diameter shield machines have gone to more countries along the "the Belt and Road" and continue to write a new legend of "Made in China" deep underground. Editor/Yang Beihua