The Union Defence Ministry will fund 20% of the project cost of the upcoming tunnel under the Brahmaputra River in central Assam, Chief Minister Himanta Biswa Sarma said on Saturday, 4 November. Addressing a press conference to give updates on several major infrastructure projects in the state approved by the centre, he said that the work on the project will start soon.
The road-rail tunnel under Brahmaputra will connect National Highway 52 at Gohpur on the north bank with National Highway 37 at Numarigarh on the south bank of the river, reducing the distance between the two towns from 220 km to 35 km only. Giving details of the project, Himanta Biswa Sarma said that 20% of the project cost will be funded by the defence ministry. The rest 80% will be funded by the highway ministry.
The project is estimated to cost ₹6,000 crore, which means the defence ministry will fund around ₹1,200 crore. The final cost will be determined after the DPR (Detailed Project Report) for the project is prepared.
As the military will be a major user of the tunnel, the defence ministry has decided to contribute to the project to ensure its earlier completion, the CM said. He added that the project has been finally approved by the central govt, and will now move onto the implementation phase.
Earlier in June, the Assam CM had said that if everything goes as planned, the construction of the underwater tunnel will begin during the term of his current govt.
It is notable that both a bridge over the river and a tunnel under it were considered to connect Gohpur and Numaligarh. Indian Army preferred a tunnel, given the strategic importance of the location, as bridges are seen as weak links that can be easily taken out by enemy bombs. In the planning stage for several years, the project was delayed because the centre was deliberating between the tunnel and the bridge, which would have been a cheaper option. However, at last, the tunnel was approved after several cabinet ministers supported the plan, considering its strategic importance.
According to reports, there will be three separate tunnels, one for road, the second one for rail, and the third one for emergency use including military transport. The tunnels, including the 11.4 km long main tunnels, will be around 15 km long and will be around 32 meters below the riverbed.
The proposal for a tunnel was originally floated by the Border Roads Organization (BRO), considering its strategic importance. BRO started surveys for the project in 2014 and selected two sites, Tezpur-Nagaon and Gohpur-Numaligarh. In 2020, the centre gave in-principle approval for the project, after which detailed studies were conducted, including an airborne electromagnetic survey.
Initially, the Tezpur site was favoured, as the river is narrower there, and the headquarters of the GOC 4 Corps of the Indian Army is located in Tezpur. However, later the Gohpur-Numaligarh location was selected, around 100 km upstream, where a bridge was already planned.
There are already two road bridges over the Brahmaputra at Tezpur, and a Railway bridge has been planned. Therefore, the Gohpur-Numaligarh location was selected, and now the tunnel will come up there instead of a bridge.
The project will be undertaken under the Special Accelerated Road Development Programme (SARDP-NE) of the Union Ministry of Road Transport & Highways.
The centre has entrusted NHIDCL (National Highways and Infrastructure Development Corporation Ltd.) with the project. The NHIDCL has floated tenders to prepare DPR and will start pre-construction activities for the construction of the tunnel soon. 4-lane approach roads on both ends of the tunnel are part of the project.
Tunnel Boring Machine will be deployed for the main tunnel under the river, while the open cut and cover method will be used for the sections of the tunnels on both ends. The length of the main tunnel will be 11.4 km, with a total length of around 15 km.
Artificial islands are also proposed on the northern and southern sides of the river Brahmaputra, and the construction zone will be created within the islands to facilitate the construction of the tunnel and also during the operational phase. The islands will act as bunds to prevent flood water from entering the tunnels.
