In the early morning of 12 November 2023, a 57 metre wide section of an under-construction road tunnel in Uttarakhand – a Himalayan state in northern India – suddenly collapsed. A heap of sediments and boulders blocked the tunnel entrance, trapping 41 workers.
Over the following 17 days, the world watched as state, national, and international organisations worked with experts, and “rat-hole” miners to achieve the final breakthrough to rescue all 41 workers.
The success of the rescue, though, overshadowed persistent complaints about design and construction in the 4.53-kilometre tunnel being constructed between Silkyara and Barkot, in Uttarakhand.
The tunnel did not have the mandatory escape passage that could have assisted with the rescue. Moreover, the tunnel’s alignment is along shear zones. These are zones formed by highly deformed, and poor-quality rock masses that may collapse if not secured well during construction, said engineering geologist Varun Adhikari – one of the experts involved in the rescue at Silkyara.
In an emailed response to queries sent by The Third Pole, authorities at the National Highways and Infrastructure Development Corporation Limited (NHIDCL), the agency overseeing the project’s execution, said that the construction “adopted necessary support [measures] and safety norms as per IRC [Indian Roads Congress] guidelines”. It further added that based on “the recommendation of [the] Authority Engineer [who is responsible for taking critical construction-related decisions], necessary supporting measures were taken…to overcome the sheared zone problems”.
However, in a LinkedIn post a day after the collapse, Adhikari pointed out faults in the reprofiling work, which is the work done in the tunnel to ensure it matches the required design dimensions. His post alleged that this work “was done in a haphazard manner”.
An expert who assisted during the rescue at Silkyara, speaking on the condition of anonymity to The Third Pole, said that construction norms were overlooked to speed up completion and cut costs. An engineer working with NHIDCL, again speaking on the condition of anonymity, said that the geotechnical investigation to ascertain properties of rock mass along the tunnel length was done by boring holes at three places. Pramod C Nawani, senior engineering geologist and former director at the Geological Survey of India, said that a geotechnical investigation for a 4.53-kilometre tunnel with just three holes was “insufficient and not acceptable” in the Himalayas, where rock types can be very different over even short distances.
Across the Himalayan region, a number of countries are using tunnels for large infrastructure projects like roads, railways, hydropower, irrigation, and managing water supply. But, due to such diverse types of projects that incorporate tunnelling, limited data is available on the number of tunnels, and tunnel-related accidents in the region.
A 2022 study reviewing nine tunnelling projects in the Himalayan regions of India, Pakistan, Bhutan, and Nepal looks at the problem beyond political borders. The study states that tunnelling faces challenges due to the complex interactions between several geological and geotechnical factors. Common problems are water ingress in tunnels, and accidents from tunnelling through sections with poor-quality rock, like shear zones. The study suggests “proper site exploration and careful planning” as being critical to tunnelling in the region successfully.
Why Tunnelling Norms Must Be Followed
Himanshu Thakkar, coordinator, South Asia Network on Dams, Rivers and People, emphasised that guidelines existed to ensure safety, during and after tunnelling, as well as to minimise impacts to the local population and the environment. The real problem, he told The Third Pole, was that guidelines were not thoroughly implemented, and the required assessments, especially those concerning environmental impacts, were superficially done for faster completion and cost-cutting purposes.
In the case of the Silkyara-Barkot tunnel, which is part of the 825-kilometre Char Dham national highways widening project, environment assessments have been bypassed. In any expansion of a national highway for more than 100 kilometres, a prior environmental impact assessment is necessary. But, to evade the assessment, the Char Dham project has been divided into 53 sections, each one of them less than 100 kilometres in length.
The flouted norms become that much more significant given that there have been several tunnel-related disasters in Uttarakhand.
In 2007, after the tunnel of Jaiprakash Power Ventures Limited’s 400 MW Vishnuprayag hydropower project began leaking, 12 families were relocated from Chaien village.
In 2016, Indian railway ministry’s project implementation unit, Rail Vikas Nigam Limited (RVNL), began work on a 125-kilometre railway project between the towns of Rishikesh and Karnaprayag, which required extensive tunnelling. Among the several tunnels being constructed for the project, an adit – a tunnel connecting the railway tunnels to the highway – is under-construction 100 metres from Sweeth village. Speaking to The Third Pole, a Sweeth resident, Anil Tiwari, 41, and the gram pradhan (elected village head), Rajendar Mohan, 43, alleged that several houses had been damaged by blasts from the construction.
A survey conducted in 2021 by the Uttarakhand government’s Geology and Mining Unit found minor and major damages to nearly 224 houses in the village. A copy of the survey report is with The Third Pole.
Om Prakash Malguri, Deputy General Manager, RVNL (Rishikesh-Karnaprayag project), though, told The Third Pole, that the damage was not from the blasts since a method called “controlled blasting” was used to minimise impacts, and that ground vibration monitoring tests were also conducted to keep the impacts from blasts in check.
In another village, Maroda, houses were severely damaged after slope-cutting work for the project began in 2021.
On February 7, 2021, a flood in the Rishiganga and Dhauliganga valleys in the state, left at least 204 people dead. These included up to 37 workers who died in the tunnels of the state-owned NTPC Limited’s under-construction 520 MW Tapovan Vishnugad hydropower project. The incident underlined the need for better disaster preparedness, like the installation of early warning systems.
And then, in November 2023, the Silkyara-Barkot tunnel collapsed.
Better Scientific Analysis Required To Understand Tunnel Impacts
The impacts of tunnelling in mountain areas are often hard to assess, owing to the lack of scientific data and analysis. One example of this is the town of Joshimath – where at least 868 houses have been damaged from land subsidence, or sinking. While the sinking began in 2021, most damage happened in January 2023.
Activist Atul Sati, who is a Joshimath resident, claimed that one of the key reasons behind the sinking land was the 12-kilometre under-construction head race tunnel of the Tapovan Vishnugad hydropower project.
The tunnel is about 1.1 kilometres from Joshimath, and Sati said that it may have stored water from the February 2021 flood in the Dhauliganga river. The water, he claimed, would have oozed out of Joshimath’s Marwari locality in January 2023, and left cavities in the ground that escalated the existing land sinking problem.
Preliminary assessments done by expert agencies, like the Geological Survey of India and the National Institute of Hydrology-Roorkee, have denied the project’s role in land sinking. Others disagree. Navin Juyal is one such senior geologist who has been working on the issue. He told The Third Pole, “The region has crystalline and quartzite rocks that do not have huge cavities to store large amounts of water that can sustain the heavy flow that was witnessed at Marwari for several days.” According to Juyal, the only visible cavity was the NTPC tunnel where flood water may have been stored.
Juyal said that more thorough scientific analysis by independent agencies and experts was required to understand the tunnel’s actual role in land sinking.
Tunnels Better Than Mountain Roads, Say Experts
The general consensus among experts like Juyal, senior engineering geologist Nawani, and senior geologist Charu C Pant that The Third Pole spoke to, was that tunnelling itself – as a construction technique – was not the issue so much as lapses in following guidelines. For railway and road-related tunnels, these experts said that if built by experienced agencies after conducting thorough scientific investigations and by following existing norms, such tunnels are more reliable than cutting huge swatches of hills and mountains for wide roads.
“Cutting hills and mountains for roads may make them landslide-prone, but this problem does not exist with tunnels,” said Nawani.
Moreover, the large numbers of trees cut, land acquired, and people impacted during road construction, are much less during tunnelling, he said.
Push For Infrastructure
In Uttarakhand, there is an ongoing rush for infrastructure expansion. One of the key reasons is tourism. With a population of 10 million in 2011 when the last census was conducted, Uttarakhand hosted over 54 million domestic tourists in 2022, with the Chief Minister declaring his intent to expand it to 70 million based on infrastructure projects like Char Dham. The other major project being built to cater to the large influx of pilgrims visiting important Hindu and Sikh shrines in the state, as well as tourists is the RVNL’s railway project, which involves 213 kilometres of tunnelling work.
For the Indian government, national security is an added reason to undertake such infrastructure projects. According to the Ministry of Defence, 674 kilometres of the total 825 kilometres being widened under the Char Dham project are feeder roads that lead to the Indo-China border, and hence are of strategic importance.
Construction of hydropower projects is another major infrastructure-related activity in the region. A 2019 study revealed that the commercially feasible hydropower potential of four Hindu Kush Himalayan countries – India, Nepal, Pakistan, and Bangladesh – is about 190 GW, of which only one-third has currently been tapped. In Uttarakhand, the state government-owned UJVN Limited states that hydropower projects with 4,183.10 MW installed capacity are operational, and projects with 9,706.6 MW installed capacity are under construction. With an estimated identified hydropower potential of 27,039 MW, the state and central governments continue to push for such projects.
When it comes to tunnels, depending on the design, hydropower projects may have a head race tunnel to transport water from the intake to the powerhouse for electricity generation; a tail race tunnel to release water used for electricity generation back into the river in the downstream; adits (passages) for allowing access to tunnels, and surge shafts to manage water pressure inside the tunnel. The powerhouse and desilting chambers could also require construction of large underground structures or caverns.
Engineering geologist Adhikari said, “Railway and road tunnels are built for people and vehicles. Hence, their design – from tunnel dimensions, to ventilation, and emergency features like escape tunnels – ensures some safety.”
Such safety measures might be absent in hydropower tunnels that are primarily designed to transport water, he said, posing a threat to those who build them.
Climate Disasters Present Fresh Challenges
To complicate matters, extreme rainfall events have been increasing in Uttarakhand, according to the India Meteorological Department. These increase the risks in tunnel construction and operation. On August 13, 2023, 114 workers were trapped in an under-construction railway tunnel in Shivpuri, Uttarakhand, following heavy rains that led to water being filled up in the tunnel, police personnel from the Shivpuri police outpost told The Third Pole. The workers were rescued after hours of efforts by the police.
Despite mounting risks, current tunnelling norms are yet to take into consideration climate change impacts. Matthew Westoby, a geomorphologist at the UK-based University of Plymouth has been working on extreme floods-related sediment transport problems in Uttarakhand. He told The Third Pole that muck from tunnelling – which is often illegally dumped into or along streams and rivers – could exacerbate flood hazard by being transported into rivers during extreme weather events or extreme floods.
Tunnelling may also disturb the subsurface geological flowpaths of water, altering the flow from the recharge area to the actual point of spring emergence, said Christopher Scott from the US-based Pennsylvania State University. Scott previously served as the Mountain Chair at the International Centre for Integrated Mountain Development. Across the length of RVNL’s Rishikesh-Karnaprayag railway project, reports have come of springs going dry.
During The Third Pole’s visit to Atali in December 2023, a 65-year-old resident, Dhaneshwari Devi, walked across the village, geared to work in the field. But, due to the land consumed by tunnelling for the RVNL project, there were hardly any fields left to attend. And all the springs had gone dry.
Just a few metres away was the national highway that had been widened under the Char Dham tourism project.
A resentful Dhaneshwari said, “On the earth, they are cutting the hills to provide wider roads for tourists; and beneath our feet, they are digging tunnels, also for them. Does our homeland belong to us or the tourists?”