by Nishith Agarwal
What Happened
A potentially catastrophic accident occurred in a northern state of India in late 2023 wherein 41 workers were trapped in a tunnel during construction.
The Silkyara Bendno–Barkot tunnel is being constructed under National Highways and Infrastructure Development Corporation Limited as a part of a larger project, intended to connect important pilgrimage sites in Uttarakhand, North India, with two-lane, all-weather paved roads. The tunnel is planned to be 4.5 kilometres (2.8 mi) long and will shorten the existing route by about 20 kilometres (12 mi).
At approximately 05:30 hrs on 12 November 2023, whilst under construction, a section of the Silkyara Bend–Barkot tunnel collapsed, trapping 41 construction workers inside, who were reprofiling 260m to 265m inside the tunnel from Silkyara portal. The 60 meter-long blockage occurred from a point about 200 metres (660 ft) from the entrance of the tunnel inwards.
The state government promptly launched Operation Zindagi (“life”) to save the trapped workers. However, the drilling through the debris in the tunnel had to be stopped on 17 November after hearing cracking sounds Alternative access tunnels had been started parallel and adjacent to the existing main tunnel. On 19 November, the Border Roads Organisation constructed a 1.15 kilometres (0.71 mi) road to a location on a hillock above the tunnel as plans for drilling a vertical shaft to enable a rescue were being made. Excessive rubble and obstructions caused drilling delays on 22 and 23 November, with significant repairs required to the drilling machine and its mounting platform on 23 November. On 25 November, the rescue operation faced another setback as the tunnel drilling machine broke and was stuck inside the tunnel after successfully drilling 47metres (154 ft), hampering the drilling’s further progress.
Meanwhile, Australian tunnelling expert Arnold Dix, who was part of the rescue operation, informed them that they needed to approach cautiously. Dix was called upon by the Indian government to serve as a consultant and spent many days and nights alongside rescue teams outside the tunnel.
On 27 November, alternate methods to gain access to the workers were intensified. Vertical drilling at the Silkyara end reached a depth of 32 metres (105 ft) and a third pipeline for the supply of necessities to the workers was also laid.
On 28 November, “rat-hole” miners in the rescue team broke through the remaining length of debris and pushed a pipe to the trapped workers manually. The rescue team evacuated the workers one-by-one on stretchers, throughout the day.
Lessons Derived
Leadership
The government of Uttarakhand was quick to form a six-member expert committee to investigate the cause of the tunnel collapse. The committee is being led by the director of the Uttarakhand Landslide Mitigation and Management Centre. The National Highways Authority of India also declared to conduct a safety audit of all the 29 tunnels currently under construction across the country along with a team of tunnelling experts from various organisations. However, preliminary findings of NHAI indicated the collapse may have been caused by a geological fault, known as a “shear zone”. The Border Roads Organisation said in a statement that the tunnel was being constructed in an extremely weak rock mass constituting meta-siltstone and phyllites, corroborating the NHAI verdict.
Prior to the commencement of the project, the leadership should have taken better clarity on the geological aspects of the area under development, to be prepared for any eventualities. Organisations that deal with such issues should have done deeper study of the tunnel route and associated precautions must have been brought to the fore.
More that reactive, proactive measures were essential and in that the senior leadership was found to be lacking.
Training
A word about the “rat miners” who successfully extricated the trapped miners. Rat mining, is a method generally used in Meghalaya to extract coal from narrow pits dug into the ground. The rat miners generally make holes only large enough for one person to enter.
In this challenging rescue mission in the Indian Himalayas, when heavy machinery faltered, a team with expertise in the unconventional practice of “rat-hole mining” stepped in. While augur machines made progress, skilled miners adept at navigating tight spaces played a crucial role in reaching and rescuing 41 workers trapped in a tunnel. The training imparted to these experts proved handy and was important for the final rescue activities.
It is also worthwhile to mention the mental strength and grit and determination of the trapped labourers. In the words of one rescued labour there were times when they felt restless inside the tunnel and wondered when they would be pulled out. However, they never lost hope, adding that they spent time playing games on their mobile phone, which they would charge using portable chargers slipped in through a pipe by rescuers. The workers would motivate each other to stay positive and that they would all eat their meals together. They would go for walks and practice yoga to keep active inside the tunnel, all these are indicators of mental toughness.
But it remains a cause of concern that no formal training has ever been imparted to these workers, to face such eventualities. Workers who are likely to face such challenges must be imparted with special training on mental fitness and ability to survive in such environments.
Supporting Infrastructure
The area of entrapment, measured 8.5 meters in height and two kilometres in length, was the built-up portion of the tunnel, offering safety to the labours with electricity and water supply available. Food was being provided to the men as rescuers had managed to push a six-inch diameter pipe through the debris inside the tunnel. They were receiving food, water and oxygen through a 53-meter (173 foot) pipe that was inserted through the debris. Doctors on site maintained regular contact with the men inside, giving them tips on how to remain positive and calm.
However, the infrastructure requirements for such massive rescue operations demand much more. The staging area must be equipped with better facilities to tackle onsite issues. Availability of senior officials round the clock is essential to take critical decisions based on ground realities. There should have been better communication facilities, better road connectivity, authorities should have been quick to establish control centres with better medical aids for injured rescue workers also.
Contingency Planning
The initial plan for the development project did not anticipate the complexity of building tunnels in this specific geography. Because the Himalayas are a very young mountain formation, and this particular section of the Himalayas has a mix of different rock types with different levels of strength, the construction has encountered multiple collapses and other faults. Landslides have also been increasing in recent decades as construction increases, and this is expected to get more complicated as climate change increases the intensity of rain and glacial melt flooding events.
According to investigators, the tunnel had no escape shafts for evacuation in an emergency and was built along a line which crosses a geological fault. The workers did not have any means of communication with their base when trapped inside. There were no first aid kits for emergency ration packs for such eventualities. Contingency preparation for workers who may face such situations needs to be better planned and implemented.
Technology
Use of modern technology is essential for project clearance as well ae execution. Proper area study is required for identifying geological issues, during execution technology must enable the workers with advance warnings, supervisors to be fed with timely alerts, rescue teams may be equipped with suitable gadgets to plan and execute efficiently within the shortest possible time.
Milind Raj, a robotic scientist, joined the rescue operations, claiming that he had built a robot to be sent inside the tunnel, via the six-inch lifeline pipe, to not only monitor the health of the workers but will also help in detecting hazardous gases inside, like methane. This robot could perform three tasks simultaneously -providing Internet services; monitoring mental health parameters of workers, such as stress, within 100 metres; and detecting hazardous gases inside the tunnel.
Lessons for Utilities Security Community
Such incidents are a possibility and have occurred in the past as well. In August, more than a dozen workers were killed after a bridge under construction collapsed in the northeastern state of Mizoram. In June, a four-lane concrete bridge that was being built across the River Ganges in the eastern state of Bihar collapsed within a short time of construction.
What it brings forth is that there is a greater requirement of leaders and planners to keep these factors in mind, A through study is essential and without proper clearances, such projects must not be permitted.
Training need analysis of such workers must be carried out and essential training on confined space working, mental fitness, survival techniques, etc must be imparted. Only adequately trained manpower must be employed in dangerous projects. Even the project leaders for such projects need to trained and experienced enough to take well-informed decisions. Refresher trainings must be carried out periodically, embedding latest technological developments and lessons learnt from accidents/ incidents world over. The emergency contact numbers must be revised and checked for veracity, to keep the data live.
Use of technology must be employed to keep the teams safe and equip them with optimal task accomplishment. Proactive utilisation of technology will result in better and safer execution. Upskilling of operators on various technological developments is critical and essential.
The rescue operations must be well-coordinated and alternate plans must be employed without any delay. However foolproof a plan may appear, issues and equipment involved are far too many and may breakdown at any time. Over-reliance on one plan may prove catastrophic. There should be a core team of well-trained professionals, for all eventualities. They should be positioned onsite without any delay. Such teams may be constituted internationally, for quick deployment.
Last but not the least, severe punitive actions must be initiated against defaulters, for deterrence against repetitions.