Voice from inside one of India's widest tunnels: ‘Can't build by fighting with rock'

Indian Express

2 days ago

There are many stories behind the 4.89-km-long, eight-lane tunnel on the Delhi-Mumbai Expressway that cuts through Mukundra Hills in Rajasthan's Kota.
One of them is that of 58-year-old Madhukar, who has built tunnels all his life. He started this project during Covid in 2021 at the north end, in what could well be his last assignment before retirement in two years. Now, faced with a difficult 500m stretch — he calls it the 'nala portion' — Madhukar is determined to complete his ninth project successfully, and gets emotional while recounting his association with the tunnel.
The tunnel, which falls between Ummedpura and Nayagaon village in Kota, is a key link of the Delhi-Mumbai Expressway — one of the most ambitious projects of the National Highway Authority of India (NHAI) under the Bharatmala Pariyojna. With a width of 22 metres and a height of 11 metres, it is also one of the widest tunnels in the country, passing through different rock masses and substrata that include sandstone, shale, siltstone, mudstone and limestone.
In the project cluster, which is divided into 53 packages, the Ummedpura-Nayagaon tunnel is being constructed by a joint venture of Dilip Buildcon Limited and Altis-Holding Corporation. It was originally a 30-month project scheduled to be completed in January 2024, but got delayed due to challenges during excavation and is now likely to be completed by the year-end.
'Hum rock se dosti karte hain, aap rock se dushmani karke tunnel nahi bana sakte (We befriend the rock, you can't make a tunnel by fighting with the rock). In this project also, we have come to the most difficult part, but we will pass it slowly. We have to just understand the behaviour of the rock,' said Madhukar, a resident of Khagaria in Bihar, who is in charge of the blasting.
Having worked in difficult terrains across Sikkim, Uttarakhand, Mizoram and Himachal Pradesh, Madhukar, who holds a diploma in mining, deconstructs the challenge. 'The top surface of the hill is in a zig-zag shape. We have come to a point where the distance between the top of the tunnel and the surface of the mountain is just 10.62m. Technically, we call it overburden. So, if not dealt with carefully, it may collapse anytime. For this, we are using a pilot tunneling methodology, where we first excavate a smaller tunnel in advance of the main tunnel's construction,' he said.
The tunnel is part of 8.3-km Package-15 of the 1,386-km expressway project. According to NHAI, the owning authority of the expressway, the cost of the tunnel was Rs 1,000 crore before being revised to Rs 1,250 crore.
Sanjay Kumar, project head and general manager (Engineering Tunnel) of Dilip Buildcon, said the tunnel is almost 80 per cent complete. 'This 8.3 km stretch of the expressway involves the construction of the highway, an open ramp, a covered tunnel and an underground tunnel. The total length of the underground tunnel is 3.3 km. On the north side, there is a 480m cut & cover tunnel. On the south portal, we have built a 1,084m cut & cover tunnel. Cut & cover is a camouflaged tunnel, which was later made part of the project as per suggestions from the Forest department as it traverses the protected area. This will help animals to pass from one side to another without disturbing the habitat,' said Kumar.
'In tunneling, and especially for such fragile stretches, we have to decide our next step at every metre of excavation. In this 500m section, we are building a smaller tunnel, then we will widen it to take the shape of the main tunnel. It is like making a tunnel inside a tunnel. Currently, on an average, we are excavating 1.2m per day. After that, we will do benching, where the lower part will be excavated. After its completion, it will connect Chechat in Rajasthan to Ratlam in Madhya Pradesh,' said Kumar, the project head.
Vikas Prasad, a geologist from Jharkhand, explains the challenges. 'The rock mass is very weak and highly fractured, Because of this, we had to face some unforeseen changes in the geological condition. There was very heavy ground water ingress inside the tunnel. Along with this, due to heavy rainfall, the tunnel submerged in 2022, 2023 and 2024. When we started work, we thought we would get hard strata but the rock formation is soft. Also, we have to give a 100-year guarantee that the tunnel will remain safe,' said Prasad.
Surendra Singh, the safety expert, said that since excavation is nearing completion, the next step is to install a robust safety system. 'The tunnel will be equipped with the SCADA (supervisory control and data acquisition) system. It will have power supply, ventilation system, fire fighting and hydrant system, fire alarm, gas suppression system, optical linear heat detection, public address, CCTV, emergency telephone, gas sensor, radio rebroadcasting system, signages, emergency power, communication & traffic control, lighting etc,' said Singh.
Pardeep Atri, regional officer, NHAI, Jaipur, said the breakthrough was completed on February 20 and April 10. 'The tunnel breakthrough is a sensational moment, when the tunnel being excavated from both sides finally meets. At this moment, for the first time, the air gushes from one side to another and increases the oxygen level,' he said.
According to Atri, this tunnel is in an eco-sensitive zone, due to which there were concerns from the forest and wildlife department. 'We redesigned the project accordingly. Most of the tunnels in the country are four-lane. We are building two four-lane tunnels here, which will be a great achievement for the more than 2,000 people who worked on this project. Vehicle movement will start from these tunnels by March 2026,' he said.
Dheeraj Mishra is a Principal correspondent with The Indian Express, Business Bureau. He covers India's two key ministries- Ministry of Railways and Ministry of Road Transport & Highways. He frequently uses the Right to Information (RTI) Act for his stories, which have resulted in many impactful reports. ... Read More