The Karnaphuli River Tunnel

Milestone

on

Bangladesh's

first

underwater

tunnel

The Karnaphuli River Tunnel in the port of Chittagong is a proposed 3.4 km-long, 11 m diameter twin tunnel under the river.

Expected to be completed in 2022, the tunnel will be the first of its kind in Bangladesh and is being implemented by the Bangladesh Bridge Authority.

The project includes over five km of connecting roads and will be a game changer for the south east region of Bangladesh, presenting a solution to connectivity issues to the rest of the country. It is also part of China’s One Belt One Road initiative and a key link in planned cross-country transport corridors.

In 2020, SMEC, together with our partners, met a key milestone after the Tunnel Boring Machine (TBM) successfully broke through at the Karnaphuli River east bank working shaft.

Delivering national infrastructure in a pandemic

The progress of tunnelling was slow, as slurry shield tunneling brings with it many risks. The TBM movement and its shield were affected by several factors, including the varying ground conditions, overburden depth, slurry pressure, primary grouting pressure, and over-excavation. In TBM slurry shield tunnelling, operators rely totally on instrumentation and sensors to guide the TBM.

SMEC, together with our partners’ specialists, supported the project contractor with their vast experience and expert advice when driving the TBM.

Client

Government of Bangladesh

Location

Bangladesh

Expertise

Tunnels Roads & Highways

The slurry shield tunnelling method used on this project is very complex and challenging due to soft soil conditions encountered. Notwithstanding, the first tunnel has been completed despite the ongoing challenges of the COVID-19 pandemic. The breakthrough of the TBM is another huge milestone which we, together with our partners, client and contractors, are very proud of.

———— Gavin Strid, SMEC’s Chief Technical Principal - Project Management