On October 7, as the shield machine's cutterhead broke through the wall, the right tube of the Bangabandhu Sheikh Mujibur Rahman Tunnel (Karnaphuli River Tunnel) project in Bangladesh was successfully holed through. The project is contracted on a general basis by China Communications Construction Company Limited (CCCC), constructed by China Road and Bridge Corporation, and built by CCCC Second Harbor Engineering Co., Ltd. With this, the tunnel has achieved breakthrough in both tubes, marking a breakthrough in China's first large-diameter underwater shield tunnel implemented overseas.

The Bangabandhu Tunnel project is located at the mouth of the Karnaphuli River in Chittagong, Bangladesh, connecting the east and west banks of the Karnaphuli River via an underwater tunnel. The route has a total length of 9.3 kilometers, a design speed of 80 kilometers per hour, and two tubes with four lanes. The shield tunnel section is 2,450 meters long, with a tunnel diameter of 11.8 meters. The project uses a slurry balance shield machine independently developed and manufactured by CCCC Tianhe. The cutterhead has a diameter of 12.12 meters; the machine is 94 meters long and weighs more than 2,200 tons in total. During excavation of the left tube, the project department overcame major construction technical challenges, including shield launching and receiving in water-rich silty fine sand strata, shield attitude control in strata that are soft at the top and hard at the bottom, and shield excavation control in iron-plate sand strata. Before the right tube was launched, based on the construction experience accumulated from the left tube, the project upgraded and modified the shield machine's cutterhead, achieving "zero cutter replacement and zero tail brush replacement" during excavation.

In the face of the severe epidemic situation in Bangladesh, the project department organized carefully, imposed strict requirements, and carried out scientific epidemic prevention, ensuring the safety of the lives of Chinese and Bangladeshi employees on the project. In the face of difficulties such as reduced flights, tight international shipping resources, and rising material prices, the project department deployed scientifically and organized in advance, ensuring that the personnel, materials, and machinery required for construction arrived on site on time. The shield machine for the right tube was launched on December 12, 2020, and completed excavation of the tunnel in only 10 months, with the tunnel "not leaking a single drop." The project's excellent construction progress and quality won high praise from the Bangladeshi owner and international consulting engineers.

The project is the first underwater tunnel in South Asia and the first large-diameter underwater shield tunnel undertaken by a Chinese enterprise overseas. The project adopts Chinese standards for design, Chinese equipment for construction, and Chinese enterprise management, and will become a shining calling card for "Chinese tunnels" overseas. As an important component of the Bangladesh-China-India-Myanmar Economic Corridor, the project is an important part of the Belt and Road Initiative. Once completed, the project will not only greatly improve traffic conditions in Chittagong and drive Bangladesh's regional economic development, but will also be of great significance for improving the Asian Highway Network, promoting connectivity between Bangladesh and neighboring countries, and advancing Bangladesh's internationalization.