Bangladesh’s first underwater tunnel officially opens

The Bangabandhu Sheikh Mujibur Rahman Tunnel – the first underwater tunnel in Bangladesh – was officially inaugurated on 28 October 2023. Owned and managed by the Bangladesh Bridge Authority, this 3.4-km-long, 11-m-diameter twin tunnel in the port city of Chattogram will play a vital role in connecting the different parts of the country and promoting economic growth.

SMEC was appointed in 2017 to undertake design review, contract management and construction supervision for the project. The tunnel was built by China Communications Construction Company under an EPC contract and SMEC led a joint venture supervision team which included ACE, COWI and DevConsultants.

The presence of soft soil in the riverbed, and an elevated water table made this a highly complex tunnelling operation, said SMEC. Passing 20 m under the Karnaphuli river, reaching 31 m deep, it is dubbed the first slurry shield under-river road tunnel in South Asia.

The ARiGATAYA system was used for data collection and management of the TBM works. It provided the SMEC team with vital information needed to make important decisions related to the operation of the TBM.

According to SMEC, it was critical to achieve watertightness throughout construction as well as during operation. Approximately 1,225 precast concrete rings have been installed to line the tunnel, each with a width of 2,000 mm and a thickness of 500 mm. The entrances of the tunnel are built to withstand cyclonic tidal surges that are common in the Bay of Bengal.

Nestled 20 m below the riverbed, the tunnel is also fitted with world-class safety and control systems to enable smooth traffic flow. A central control centre will monitor the tunnel in real time, with the ability to activate controls remotely to respond to changing conditions or any incidents that occur. The tunnel is capable of servicing approximately 28,000 vehicles a day.

In addition to the tunnel, the project features several interfacing infrastructure nodes including 5.4 km of approach roads, a 730 m viaduct, a toll plaza, overload control system, a 65 ha mixed-use service area, and a slurry treatment plant.

With the construction team peaking at over 2,000 people on site, SMEC was tasked with implementing a comprehensive management framework which extended to document control, quality assurance, safety, environmental management, and risk assurance. The team also had to navigate severe disruptions caused by the global pandemic.

Dr Janardhan Sundaram, SMEC executive director Bangladesh, said, “The tunnel is a game-changer for economic development in the region. It will ease traffic congestion and significantly reduce travel times between Dhaka, Chattogram Port and the developing growth area in southeast Bangladesh.”

Gavin Strid, SMEC chief technical principal and project manager, added, “The Bangabandhu Sheikh Mujibur Rahman Tunnel enabled the training of over 50 local Bangladeshi engineers. The project’s success has given the government confidence in the slurry shield methodology which is currently being deployed on other mega projects in the country, including the Dhaka Metro.”

Image credits:
Images 1-2: SMEC
Images 3-5: Sahiduj Jaman Saju

Note: More photos of the project can be viewed below.