Assam’s First Underwater Tunnel Gets DPR Approval, ₹6,000 Crore Project Awaits Cabinet Clearance.

Assam is poised to make engineering history with the completion of the Detailed Project Report (DPR) for the state’s first underwater tunnel, a ₹6,000 crore greenfield project that will connect Numaligarh and Gohpur by passing beneath the mighty Brahmaputra River.

Touted as India’s first-ever road tunnel to run beneath a major river, the project is now awaiting approval from the Union Cabinet, specifically the Cabinet Committee on Infrastructure headed by the Prime Minister. Once approved, the tunnel is expected to be completed in five years.

A senior Assam government official confirmed to The Economic Times, “The DPR is ready and the project will soon be placed before the Union Cabinet for final clearance.” The tunnel holds significant strategic importance, given its proximity to Arunachal Pradesh, which shares a sensitive international border with China.

Being implemented by the National Highways and Infrastructure Development Corporation Limited (NHIDCL), the project has undergone technical appraisal by the Project Appraisal and Technical Scrutiny Committee (PATSC) of the Ministry of Road Transport and Highways (MoRTH). NHIDCL also conducted a comprehensive feasibility survey and finalized the alignment of the tunnel, which will be part of a 33.7-km stretch linking Gohpur to Numaligarh.

The tunnel’s engineering is as ambitious as its scale: the crown of the tunnel is proposed to be built approximately 32 metres below the riverbed of the Brahmaputra, one of India’s deepest rivers at this stretch.

The Standing Committee of the National Board for Wildlife (NBWL), which has already cleared the project, has called for a detailed scientific analysis of its environmental impact. This includes studies on soil stability, groundwater flow, sediment dynamics, and vulnerability to seismic activity.

Officials said the underwater tunnel is being constructed under the Brahmaputra not only for connectivity but also due to strategic defence considerations. “The tunnel will significantly enhance access and mobility in a strategically vital region,” an official added.

Assam Chief Minister Himanta Biswa Sarma, who had earlier conceptualized the idea, said it was initially seen as a far-fetched dream. “There are many bridges over the Brahmaputra, but why not a tunnel under it?” he recalled. “I was later told in Delhi that it is possible. After much discussion, we decided on the Numaligarh-Gohpur stretch. This tunnel will carry both trains and vehicles, and bring the north and south banks of the Brahmaputra closer than ever.”

Once completed, the tunnel is expected to boost regional connectivity, reduce travel time, and provide a critical infrastructure link in a border-sensitive region.