The Silkyara Tunnel: A Tale of Tragedy, Rescue, and Lessons Learned
By- Dr. Mukta Girdhar, Disaster Management Expert, New Delhi. | Email:-mukta_girdhar@hotmail.com
Date On the fateful day of November 12, 2023, at 5.30 P.M. tragedy struck the serene hills of Uttarakhand, India, as a section of the Silkyara Bend–Barkot tunnel, a pivotal part of the Char Dham Pilgrimage Project, collapsed during construction. The incident, which unfolded in the Himalayan region, trapped 41 workers, shedding light on the formidable challenges and inherent risks associated with ambitious infrastructure development projects in such geologically sensitive areas.
The Silkyara Bend–Barkot Tunnel stands as a crucial component of the expansive Char Dham Pilgrimage Project. Spanning a length of 4.531 km with a 2-Lane Bi-Directional configuration, the project aims to forge connections between four significant Hindu pilgrimage sites. Beyond enhancing connectivity, its objectives include fostering regional socio-economic development while conscientiously preserving the environment by steering clear of unnecessary tree removal.
- • The tunnel is located on the Yamunotri National Highway near Silkyara and was being constructed under the Chardham Highway Project.
- • Accident spot located near Main Central Thrust of the Himalayas and this area is extremely sensitive to earthquakes and frictional shear rocks are present in this area.
- • Experts raised questions on geological and geotechnical surveys for the project and said that mainly two types of incidents occur during tunnel construction in Uttarakhand —
Sudden release of large amounts of water and Unexpected encounter of sheared rocks (worn by rubbing against each other).
Silkyara Bend-Barkot Tunnel in Uttarakhand
• Silkyara Tunnel: It is around a 4.5 Km long two-lane Bi-Directional tunnel with an escape passage on Dharasu –Yamunotri.
• Significance: This tunnel will provide all-weather connectivity to Yamunotri, encouraging regional socio-economic development, trade, and tourism within the country.
It will reduce the travel distance from Dharasu to Yamunotri by about 20 km and travel time by about an hour.
Char Dham Highway Project
• The project aims to enhance road connectivity and ensure the safety and convenience of pilgrims traveling to Uttarakhand’s 4 major shrines viz. Badrinath, Kedarnath, Gangotri, and Yamunotri.
• The project involved widening and upgrading existing roads, constructing new roads, and implementing measures to make the journey smoother and safer.
Construction and Controversies:
The Silkyara Tunnel was under the construction purview of Navayuga Engineering Construction Limited (NECL) under the aegis of the National Highways and Infrastructure Development Corporation Limited (NHIDCL). However, the project was not without scrutiny, as geological challenges and alleged deviations from approved blasting methods raised concerns about safety measures and monitoring protocols.
At approximately 5:30 IST on November 12, a segment of the tunnel crumbled, leaving 41 workers trapped 205-260 meters from the entrance due to fallen debris. The incident created a perilous situation, necessitating a rapid and coordinated response from the authorities.
In response to the crisis, the Uttarakhand administration, in collaboration with various government units, launched Operation Zindagi ("life"). The rescue mission faced immediate challenges such as food and water shortages. Authorities ingeniously supplied fresh air, oxygen, water, electricity, and small packaged foods through pipes to sustain the trapped workers in their precarious situation.
DAY 1 (12 November, 2023)
Nov 12 2023 @ 05:30 P.M a portion of Silkyara Tunnel under construction collapsed from Silkyara to Barkot due to debris falling in a 60-meter stretch on the Silkyara side, trapping 41 workers!
When time was running out, when Hope was turning into despair, On day one, after the collapse of Silkyara tunnel, trapping 41 workers, the senior most amongst them, gauged the situation, applied his mind and started the pump after seeing the tunnel getting flooded. The discharged water found its way out through the 4” diameter pipe. The rescuers thus got an indication that the trapped workers are alive and all out Rescue Operations started.
652 Gov employees from Uttarakhand State, to the NDRF, SDRF, Indian Air Force, ARMY, Border Road Organization; the Best American Machines breaking through Concrete, Best International Experts Dix, Micro Tunnel Expert Chris Cooper were all involved at site but nothing seemed to be working.
Day 2(13 November, 2023)
Communication was established with trapped workers through walkie talkies. Oxygen, water packed food was supplied to the trapped workers through pipes.
DAY 3 (14 November, 2023)
As per plan two, 800-900 mm steel pipes were brought to the tunnel site for Horizontal excavation with Auger drill. Plan was to bore through the rubble and create a passage by inserting these pipes. Drilling was started in the evening.
DAY 4 (15 November, 2023)
In order to speed up the operation a state of the American made “dry drilling equipment with auger” was airlifted from Delhi.
Day 5 (16 November, 2023 )
The machine which was brought to the spot in three parts was assembled and put in operation by mid night.
DAY 6 (17 November, 2023 )
Drilling was started through the Debris: 24 m through 57 m stretch. The machine was able to drill 24 m and 4 pipes were inserted. Then, Encountered an Obstacle ! Another high performance Auger drilling machine was brought in. But it didn’t help ! A loud cracking sound was heard in the evening while positioning the Fifth pipe. Operation was immediately suspended.
Day -7,8 (18,19 November, 2023 )
Drilling does not resume. A group of officials from the PMO along with experts, opt to pursue five evacuation plans concurrently. This includes exploring alternatives options such as vertical drilling through the tunnels top to rescue the trapped labourers.
DAY 9 (20 November, 2023 )
On the ninth day of Rescue operations at Silkyara tunnel collapse site, significant advancement was successfully pushing a Six-inch-wide pipeline through the debris to supply essential commodities to the trapped workers. This was only a first breakthrough with only the food pipe inside !
Rescue Option
Despite setbacks spanning over 240 hours near about ten days, several agencies are working in tandam on different ways to get the workers out. Finally five rescue operation came out
- Using the American auger machine to horizontally drill from the Silkyara end, the quickest way to reach the workers. Horizontal Drilling from Silkyara end using American machine
- Digging a 1.2 m wide hole vertically from above. This will need around 90m meters of digging and meet the tunnel at the 320 metre mark from the Silkyara side. 1.2 m hole being drilled vertically (90 m)
- Horizontal micro drilling from the left to make a tunnel that will be 1.2 metres wide, and 168 meters long. Horizontal micro drilling from left Side to make escape tunnel (168 m long) .
- Creating another vertical tunnel which will be 325 metres deep and meet workers near opposite end of trapped areas. Construction of escape tunnel from Barkot end
- Constructing a rescue tunnel from the Barkot end through conventional drill and blast method. Vertical drilling by ONGC
DAY 10 (21November, 2023 )
Endoscopic camera was pushed through the six-inch food pipe. First visuals of the trapped workers were received. They all appeared to be safe. The camera was used to count the trapped workers and understand the internal geography of the tunnel.
Day 11, (22 November,2023)
Horizontal drilling, using 800mm diameter steel pipes, reaches approximately 45 meters, leaving only 12 metres to cover in the 57- metres to cover in the 57-metre debris stretch. Yet in a last evening setback, the drilling is impeded by iron rods obstructing the auger machine.
Day 12 (23 November, 2023)
The iron obstacle is cleared in the morning and rescue operations resume. The state government’s nodal officer reports a 1.8 metre progress since the previous night’s setback. Drilling through the rubble is halted again due to apparent cracks in the platform supporting the machine. Officials indicate reaching the 48 metre point with the drill.
A 21-member team of National Disaster Response Force (NDRF) personnel, carrying oxygen cylinders and stretchers on their backs, entered the collapsed Uttarkashi's Silkyara tunnel earlier in the day to assist in the ongoing rescue operation. They encountered an obstacle ~ a hard rock ! The drilling gained momentum after breaking through a rock formation that had posed a significant obstacle, causing a day-long delay in rescue operations. The teams utilised 900 mm pipes to reach a depth of 24 metres. Beyond that, they employed 800 mm pipes to advance further to 36 metres.
Day 13 (24November2023)
Drilling recommences however, a new obstacles arises as the boring progress for about an hour before the drill encounters a metal girder, causing the auger machine to break down. Drilling continued as the pipe had covered 44 meters and it still had 12 meters to go.
The obstacle now was that a few steel pieces had come into the debris, so the steel pipes had to be cut out.
Day 14 (25November 2023)
International tunnelling expert Arnold Dix says the auger machine is busted and completely broken down beyond repairs. Authorities were considering other options to evacuate the trapped workers. Rescuers are considering other option, including vertical and manual drilling to bring out the trapped workers. Rescuers prepare to start vertical drilling. He gave a timeline of X-mas for the rescue of 41 workers. That would have been disastrous !!!
Day 15 (26November 2023)
Rescuers being drilling into the hill above the Silkyara-Barkot tunnel, By evening, the heavy drilling equipments had bores down to about 19.5 metres.
Day 16 (27 November 2023)
Rat hole mining is a method of manual drilling , carried out by experienced workers, most common in Meghalaya. Narrow pits are dug into the ground, usually just wide enough for one person to fit into as it poses significant safety and environmental hazards, it is banned in India
“Rat miners” Called into resume horizontal drilling manually. It involved rescue workers entering the roughly to and a half foot pipe already inserted into the debris pile and manually extracting the remaining rock and soil using hand tools. They achieved the feat within 24 hours, excavated the debris with hand tools, reinforced it and brought out all the 41 trapped workers – one by one with the help of wheeled stretchers
Hats off to the Rat Miners for their grit, determination & courage and unwavering commitment to save lives They didn’t charge any money for the historic Rescue Operation !
Day 17 (28 November 2023)
Break through finally all workers have been rescued. 12 member team of rat hole mining experts that rescued 41 workers from Silkyara tunnels in 28 hours. Names are Feroz Quershi, Munna, Rashid, Inshad, Naseem, Monu, Naseer, Ankur, Jatin, Saurabh, Waqeel Hasan, Devender.
They showed what hard work and determination could do where modern machinery had failed ! On Nov 28, all 41 workers who had been confined in partially collapsed Silkyara Tunnel were successfully freed on 17th Day of Rescue. The first worker came out at 07:56 pm, followed by others.
The 2.0 km long tunnel presented formidable challenges. Technical difficulties forced to switch to manual drilling to remove the last 10 meters of Debris, as early attempts to use advanced drilling techniques with Auger drill had failed !
Twelve Rat Hole Mining experts used handheld tools in confined space acknowledging the contentious nature and associated risk of working in narrow passages.
Workers were rescued on wheeled stretchers in a narrow pipe as illustrated. Using a steel chute inserted into the drilled passage, NDRF personnel carried out a methodical extraction.
The amazing example of team work won the appreciation of all including the PM !
Finally the Rescue has seen , Light At The End Of The Tunnel ! All the 41 workers were finally Rescued, hale and hearty ! Excellent arrangements made by the state authorities were 41 ambulances to transport them straight to the AIIMS Hospital, under medical care for two days and then allowed them to go home in chartered planes.
International Assistance and Challenges:
Recognizing the complexity of the rescue operation, international experts, including Australian underground expert Arnold Dix, were enlisted. The intricate terrain, ongoing landslides, and the breakdown of the main drilling machine added layers of complexity to the rescue efforts.
Success and Lessons Learned: The multi-pronged rescue operation bore fruit on November 28, 2023, when all 41 workers were successfully evacuated. The incident emphasized the critical role of geological assessments, adherence to safety protocols, community engagement, and the integration of advanced technologies in preventing similar disasters.
Infrastructure Development in the Himalayas: While the Char Dham project and analogous infrastructure endeavors aim to advance connectivity, they have faced criticism for their impact on the geologically unstable Himalayan terrain. Environmentalists advocate for a "terrain-specific approach" and stress the necessity of creating disaster and climate-resilient infrastructure.
Legal Challenges and Supreme Court's Role: Legal challenges have marred the Char Dham project, with concerns over bypassing environmental assessments. The Supreme Court's involvement has been pivotal, though debates persist, particularly regarding the pavement width, showcasing the ongoing struggle between development and environmental conservation in the fragile Himalayan ecology.
Causes
The preliminary probe report on the recent Silkyara tunnel collapse in Uttarkashi has found multiple reasons for the accident, including wrong alignment of the project with it being along the 'shear zone' and the contractor carrying out 're-profiling' work without taking adequate safeguards despite knowing vulnerabilities of the stretch going by past records of cavities (collapses).
Inadequate deployment of sensors and instruments, which capture ground behaviour during the re-profiling work, so that necessary precautions could have been taken. The collapse also highlighted the lack of proper supervision on the part of the officials of the National Highway and Infrastructure Development Corporation (NHIDCL), a company under the road transport ministry, and its authority engineer.
Conclusion:
The Silkyara Tunnel accident serves as a poignant case study in disaster management, underscoring the imperative for meticulous planning, strict adherence to safety measures, and a proactive approach to address geological challenges. It prompts a contemplation of the delicate balance required between infrastructure development and environmental preservation in vulnerable regions like the Himalayas. The incident stands as a stark reminder that progress must be achieved without compromising the delicate equilibrium of nature in these sensitive areas.
References:
2.https://en.wikipedia.org/wiki/Uttarakhand_tunnel_rescue
3. https://www.science.org/doi/10.1126/science.adn6360
4. Down to earth
Dr. Mukta Girdhar, Disaster Management Expert, New Delhi.
(This "EXPERT TALK" Published in February 2024 Edition)
