The pace of overall tunnel construction in the country has accelerated in recent years, especially in sectors such as metro, hydropower, etc. Increasing urbanisation and the consequent need for better infrastructure have led to an increase in the scope of tunnelling projects. However, tunnel growth in the roads and highways sector has been slow, with only a few tunnels being built in mountainous areas.
The government aims to complete tunnel projects totalling 331 km by 2026. The Ministry of Road Transport and Highways, the Ministry of Railways, and the Border Roads Organisation have recently come on board for construction of the country’s first underwater road-cum-rail tunnels across the Brahmaputra river in Assam. There will be three parallel tunnels – for road traffic, rail traffic and emergency traffic. The project is estimated to cost Rs 70 billion.
Project strides
The Mumbai Coastal Road Project, which spans 29.2 km and connects south Mumbai to the Bandra-Worli Sea Link at the Worli end, includes a tunnel, a road and an interchange. The first undersea tunnel in India, it comprises a pair of twin tunnels, one northbound and one southbound, each 2.07 km in length. In the budget for 2022-23, the Brihanmumbai Municipal Corporation (BMC) allocated Rs 32 billion for this project. As of July 2022, about 58 per cent of the overall project work has been completed and it is expected to be ready by November 2023. The tunnel from Priyadarshini Park to Netaji Subhash Marg (Marine Drive) has already been completed and 39 per cent of work on the tunnel on the other side has also been completed. BMC plans to reclaim a 111 hectare area in the Arabian Sea. Of the 175 monopiles to be constructed under the bridges, 70 have been built.
The central government inaugurated the Bhagwan Das-Purana Qila (Delhi) Tunnel Project, also known as the Pragati Maidan Integrated Transit Corridor Project, on June 19, 2022. The project involves the construction of a 1.6 km long six-lane tunnel and six underpasses at a cost of Rs 9.2 billion.
In a recent development, the National Highways Authority of India has proposed the construction of a 4,891 metre long twin-tube tunnel with ramps on both sides of the tunnel near Mukundra, Rajasthan, on the Delhi-Vadodara eight-lane expressway. In addition, an ambitious project to construct tunnels and bridges to link the Kashmir Valley to Ladakh is under way.
Challenges
A number of challenges are involved in urban tunnelling. These include land acquisition issues in an urban set-up, limitations with gradients and curvature to meet the existing urban set-up, restrictions in the handling and operation of equipment, inadequate space availability, equipment transportation challenges, space for shaft construction, and structural health monitoring. Some of the common technical problems in tunnel execution are high water ingress, portal collapse, face collapse and chimney formation, ground squeezing, and rock burst.
Key upcoming projects
Some of the key upcoming road tunnel projects are the twin tunnel for the Goregaon-Mulund link road project in Maharashtra, a two-lane tunnel at the Sudhmahadev and Sinthan pass and the Gurez tunnel project (Razdhan pass) in Jammu & Kashmir, and the Sakleshpur-Gundya tunnel road in Karnataka. Hyderabad will soon have the country’s longest highway road tunnel, stretching around 10 km from Jubilee Hills Road No. 45 Junction to Banjara Hills Road No. 12 Junction. The proposed four-lane tunnel will be excavated using a tunnel boring machine and will extend from the KBR Park Junction to the NFCL Junction in Punjagutta via the KBR Park Junction.
India will also be home to the world’s longest highway tunnel beneath the 16,580 foot high Shinku-La pass (the world’s longest and highest pass) between the Zanskar valley in Ladakh and Lahaul valley in Himachal Pradesh. The tunnel is expected to be completed by 2025 and will provide all-weather connectivity between Ladakh and Himachal Pradesh. These will provide immense opportunities to tunnel contractors, consultants, equipment providers and material suppliers. w
With inputs from Sandeep Singh, Project Manager (Mumbai Coastal Road Package 4), Larsen & Toubro, and Purnachanda Bhave, General Manager, Afcons Infrastructure, at a recent India Infrastructure conference