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Journalism of Courage
“Dhyaan se. Koi galti na ho (Be careful. Don’t make mistakes),” Vivek Kumar’s words of caution, shouted from atop a telehandler machine that is used to carry heavy loads, bounce around the quartz black tunnel, where workers are installing explosive charges to make space for an electric room.
Inside what is slated to be India’s longest transportation tunnel in Uttarakhand’s Devprayag, the 14.57-km Janasu twin tunnel, also known as tunnel no 8 (T-8), the race is against both time and the uncertainty of Himalayan geology. A part of the 125-km Rishikesh-Karnaprayag line, T-8 is located on the Devprayag-Janasu stretch.
Moving ahead with a box of explosive fuse, Kumar, a blaster from Bihar, tells The Indian Express, “The tunnel is almost complete. Only some work, like electric rooms, is pending. We have been directed to complete them as soon as possible so that track work can start.”
A few minutes and a big boom later, the explosives have blown a clean, 1.5-metre hole in the quartzitic phyllite rock. The cleared space will house one of the five electric rooms that will power lights, fans and other electrical equipment inside the tunnel.
From mobilising a “factory-sized” 2,200-tonne tunnel boring machine (TBM) to excavate hard rocks to make tunnels to using three types of technologies to dig through the vagaries Himalayan geology — the making of T-8 has been one of the most challenging projects undertaken by Indian Railways so far.
On April 16, T-8 completed the critical tunnel breakthrough phase, witnessed by Union Railways Minister Ashwini Vaishnaw and Uttarakhand Chief Minister Pushkar Singh Dhami. A tunnel breakthrough marks the point when a tunnel being excavated from both ends finally connects. The breakthrough coincided with a significant date for the Railways — on April 16, 1853, India’s first train ran between Bori Bunder (now Mumbai) and Thane.
While the project is a single-line broad-gauge network, the planners have a double line in this tunnel, considering the future requirement. The breakthrough of one T-8 tunnel is complete and the excavation of the second tunnel by TBM has reached up to 8.70 km. It is scheduled to be completed in June. To ensure its timely completion, the Rail Vikas Nigam Limited (RVNL), a navratna public sector undertaking (PSU) under the Railways Ministry tasked with implementing the Rishikesh-Karnaprayag project, has set a target of excavating at least 30 metres daily.
At present, India’s longest rail tunnel is the 12.77-km T-50, which lies between Khari and Sumber stations on the Katra-Banihal section of the Udhampur-Srinagar-Baramulla Rail Link (USBRL), also known as the Kashmir line.
Pradeep Gaur, chairperson and managing director of RVNL says the Rishikesh-Karnaprayag project holds huge strategic importance since it is a gateway to the China border and it will also facilitate Char Dham Yatra.
“The project will provide a safe mode of travel because roads in hills are always prone to landslides. Save for the yards, the entire line is virtually underground, making it an all-weather option,” he says.
Though surveys for a rail line across Uttarakhand’s Himalayan terrain started in 1996, all attempts were met with failure over the years. In September 2011, Indian Railways tasked the RVNL with implementing the project, which awarded the T-8 contract to Larsen & Toubro (L&T) in 2021. From 2016 to 2019, RVNL conducted a detailed survey for the alignment. While the anticipated cost of the entire project was Rs. 16,216 crore, sources say the expenditure is expected to cross Rs 35,000 crore.
Tunnels stretch over 104 km or 83% of the 125-km line. The single-line broad-gauge network is expected to have 12 new stations, 16 main tunnels and 19 major bridges spanning five Uttarakhand districts — Dehradun, Tehri Garhwal, Pauri Garhwal, Rudraprayag and Chamoli. The line is expected to cut travel time from seven hours to two.
Located on the banks of the Ganga, almost 2 km from the confluence of Alaknanda and Bhagirathi, T-8 is a hive of activity. Two large exhaust fans for ventilation are mounted on a gantry (tall metal frame used to support a crane) at the tunnel’s 20-metre wide gate, where a skid loader is moving debris and conveyor belts along the ceiling are transporting the muck from the shaft’s excavation points.
Multiple 10-km-long pipes along the floor carry water cooled to 5 degrees Celsius from a chiller plant outside to cool the TBM inside, and cement and sodium silicate to join the segments in the tunnel, even as trucks with sirens ferry materials in and out of the tunnel.
Issuing frantic instructions over walkie-talkie are site supervisors as Brokk, a remote-controlled demolition machine, breaks rocks at one section. Through the murky concrete surface and hazy surroundings, e-rickshaws ferry workers in and out the tunnel. At present, around 2,500 workers have been deployed at the site.
T-8 also has the distinction of being the first place in the Himalayas where Indian Railways has used TBMs to excavate hard rocks to make tunnels. An L&T employee says that earlier TBM was used in Himalayan hydropower projects like Pipalkoti and Tapovan in the state’s Chamoli district.
Unlike the blasting method, a TBM reduces both disturbance to surrounding areas and the cost of lining the tunnel. A TBM was used during the construction of the Delhi Metro too. While the diameter of that TBM was around 6 metres, the diameter of the T-8 TBM is 9.1 metres.
According to B Kiran Kumar, deputy manager and site incharge, the most difficult part of the project was the mobilisation of resources. Kumar, who joined the site in 2023, says, “The TBM is not just a machine; it’s a factory. It is 180 metres long and weighs 2,200 tonnes. It took 17 shipments to send the parts of two TBMs from Germany to Gujarat’s Mundra Port. Over 100 trucks and trailers then carried these parts — the most heavy shipment weighing over 200 tonnes — to the site, where 25 people worked for eight weeks to assemble just one TBM. Before it arrived, we had to load test the old bridge (the first bridge on the Ganga) to check if it could bear the shipment’s weight.”
Besides the TBM, the New Austrian Tunnelling Method (NATM) was also used to excavate T-8. Used for making tunnels on the Katra-Banihal section earlier, NATM involves blasting and small-scale excavation. While the TBM tunnelled 10.4 km of T-8, 4.11 km was excavated using NATM.
“Since TBM works only in uniform geology, a 10.4-km stretch in the tunnel with the same rock formation was excavated by the TBM. The Himalayas are fragile mountains, full of uncertainties, and you never know what challenges you may face inside the tunnel. Which is why, we used three new technologies — tunnel seismic prediction (TSP), torque box and void measurement — in the TBM for this excavation,” says Himanshu Arora of L&T, who is also the project manager for the TBM.
While TSP helped them identify geological uncertainties in the rock mass, says Arora, the torque box cylinders in the TBM allowed both horizontal and vertical movement, ensuring precise boring. “This is important because TBM excavations can, at times, lead to gaps between excavated rock and installed tunnel lining. Void measurement helps us fill these gaps and provide a continuous interface,” he says.
Stating that two TBMs were deployed for tunnelling work, an RVNL employee adds, “Though work on this tunnel started in 2021, the TBM was pressed into use at the end of 2022. This TMB has 55 disk cutters, which excavate around 34 mm in one round and 78 mm in a minute. The machine has 1,500 in-built sensors that record data every three seconds. On average, the machine excavated 413 metres per month. On its best day, the TBM excavated 42.5 metres in a day and 550 metres in a month.”
Arora, who says the TBM was allowed to “rest” for a few hours after every 50 metres of excavation, giving them time to clean up, says the biggest “challenge” while excavating was to prevent tunnel collapse. He adds, “Because of the Himalayan geology, as you keep excavating, the biggest danger is the tunnel shrinking or squeezing in, resulting in its collapse. So excavation and covering the tunnel with a precast segment in a ring shape happened simultaneously. TBM helps expedite the whole process. Another major challenge was our encounter with a massive quantity of water flowing at a speed 1,500 litres per minute out of nowhere from the mountain. Since the alignment of the line is upward, the water flowed down. Else, our hard work would have been wasted.”
Deepak Shah, a mechanic from Bihar’s Sitamarhi, however appears unfazed by the “grandiose” tunnel. He says, “My supervisor says this is the longest (rail) tunnel in the country. It does not matter whether a project is big or small. What matters is how many days of work I get on a project.”
