 | |
 | |
| Date |
|
|---|---|
| Time | 05:30 IST |
| Location | Silkyara Bend–Barkot tunnel,Uttarkashi, Uttarakhand, India |
| Coordinates | 30°45′26.9″N78°15′48.8″E / 30.757472°N 78.263556°E /30.757472; 78.263556 |
| Cause | Tunnel collapse |
| Outcome | All 41 trapped workers rescued |
On 12 November 2023, a section of the Silkyara Bend–Barkot tunnel, planned to connectNational Highway 134 in theUttarkashi district of Uttarakhand, India,caved in during construction. The collapse occurred at around 05:30IST and trapped 41 workers inside the tunnel.[1][2]
Rescue operations were immediately launched, with a number of government agencies involved, including theNational Disaster Response Force, theState Disaster Response Force,Uttarakhand Police, engineers from theIndian Army Corps of Engineers, andProject Shivalik of theBorder Roads Organisation.[3][4][5][6] Numerous private resources were utilized in the rescue efforts as well, including Australian tunnelling expertsArnold Dix and Chris Cooper.[7][8]
Though the initial attempts at a rescue were complicated because of the kinds of debris created in the collapse, the government brought in"rat-hole" miners who were able to use manual mining methods to get an access pipe to the trapped workers.[9] All 41 workers were rescued, and the collapse triggered a safety audit of other tunnels in the area.
The Silkyara Bend–Barkot tunnel was being constructed by contentious[10] Navayuga Engineering Construction Limited (NECL) underNational Highways and Infrastructure Development Corporation Limited (NHIDCL)[11] as part of theChar Dham project, intended to connect important Hindu pilgrim sites in Uttarakhand,North India, with two-lane, all-weather paved roads.[12] The tunnel was located on theYamunotri end ofNational Highway 134, which is planned to connectDharasu on the south end to Yamunotri on the north end. The tunnel is planned to be 4.5 kilometres (2.8 mi) long[13] and will shorten the route by about 20 kilometres (12 mi).[14][15]
The initial tender for the development project did not anticipate the complexity of building tunnels in this specific geography.[12] 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.[12] 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.[12]
At approximately 5:30 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.[16] The 60 meter-long blockage occurred from a point about 200 metres (660 ft) from the entrance of the tunnel inwards.[12][17] A team of geologists from the state government of Uttarakhand and educational institutions was sent to the location to determine the cause of the incident.[18] According to investigators, the tunnel had no escape shafts for evacuation in an emergency and was built along a line which crosses ageological fault.[19]
The tunnel's location is in proximity to themain central thrust of theHimalayas which is a major geological fault and is generally accepted to be ashear zone. The Border Roads Organisation said in a statement that the tunnel was being constructed in an extremely weak rock mass constitutingmeta-siltstone andphyllites.[20][21]
The state government launched Operation Zindagi ("life") to save the trapped workers.[citation needed] On 16 November, another horizontal drilling machine with an auger bit (to install an 800mm escape pipe) was disassembled and flown from Delhi in three parts after the progress of the first machine was insufficiently speedy.[22][23] The rescue team had contacted the team that freed the students from the 2018Tham Luang cave disaster inThailand.[24]
Drilling through the debris in the tunnel was stopped on 17 November after cracking sounds were heard. Alternative access tunnels had been started parallel and adjacent to the existing main tunnel.[25] Three pipes were drilled during the operation, one providing oxygen, one providing passage for food, and a 15-centimetre-wide (6 in) pipe that was used to supply hot meals and allow the insertion of an endoscopic camera.[26] On 19 November, the Border Roads Organisation constructed a 1.15 kilometres (0.71 mi) road to a location on ahillock above the tunnel as plans for drilling a vertical shaft to enable a rescue were being made.[27]
Problems with the consistency of the rubble and with obstructions caused drilling delays on 22 and 23 November, with significant repairs required to the drilling machine and its mounting platform on 23 November; at this stage, it was believed that the operations had reached 75% of the way through the obstructing debris.[28] On 25 November, the rescue operation faced another setback as the tunnel drilling machine broke and became stuck inside the tunnel after successfully drilling 47 metres (154 ft), hampering the drilling's progress. The rescue team decided to use manual tools such as hammers and chisels to break the debris and reach the trapped workers. It was believed that the drilling had reached a point approximately 9 metres (30 ft) short of breaking through.[29][30] Meanwhile, Australian tunnelling expertArnold Dix, who was part of the rescue operation, informed them that they needed to approach cautiously.[31] 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.[32]
On 27 November, alternate methods to gain access to the workers were intensified. Vertical drilling bySatluj Jal Vidyut Nigam 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 being laid byRail Vikas Nigam. On the Barkot end of the tunnel,THDC India Limited had executed a successful drill up to 12 metres (39 ft) whileOil and Natural Gas Corporation was preparing for vertical drilling.[33]
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.[9] The rescue team evacuated the workers one-by-one on stretchers, throughout the day, in a process that was expected to take several hours.[34]
Later at around 20:50IST on the same day, it was confirmed by theGovernment of Uttarakhand that all 41 workers had been successfully rescued.[35] The chief minister of UttarakhandPushkar Singh Dhami and Minister of State of Road Transport and HighwaysV. K. Singh were present at the site welcoming the rescued workers.[36]
The rescued workers were reported to be in good health, and they were taken to a medical facility inChinyalisaur for initial assessment.[37] Forty-one ambulances were arranged for the individuals.
On 29 November, the 41 rescued workers were airlifted toAIIMS Rishikesh aboard anIndian Air ForceCH-47 Chinook helicopter for further assessment.[38] Following a medical examination, 40 of those workers were declared fit and cleared to return home as of 1 December.[39]
The government of Uttarakhand has formed 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.[40]
On 22 November, theNational Highways Authority of India said in a statement that it will conduct a safety audit of all the 29 tunnels currently under construction across the country along with a team of tunnelling experts fromDelhi Metro Rail Corporation.[41][42] However, preliminary findings of NHAI indicated the collapse may have been caused by a geological fault, known as a "shear zone".[43]
Although the detailed probe report into the collapse found negligence on the part of NHIDCL, the entity that prepared the Detailed Project Report (DPR), as well as the construction firm and the supervising consultant or authority engineer (AE), the government has yet to take any significant action against these entities. The report highlighted that the alignment fixing did not adhere to the fundamental principles of tunneling, and there was negligence from the contractor in addressing the issues related to 21 minor collapses, even though the AE had flagged them.[44]
PresidentDroupadi Murmu and Prime MinisterNarendra Modi expressed relief for the successful rescue and wished the workers good health. They also appreciated the efforts of numerous agencies and personnel involved in the rescue operation.[45][46][47]
TheAustralian High Commissioner to IndiaPhilip Green andAustralian Prime MinisterAnthony Albanese congratulated Indian agencies for evacuating the 41 trapped workers. They also commended the efforts made by Dix for providing technical expertise.[48][49]
On 16 April 2025 multiple media outlets reported that the two ends of Silkyara have met i.e. breakthrough has been achieved. With this breakthrough the excavation work will be completed and the tunnel will be ready for use in the next one year after finishing the remaining works. The restoration of the collapsed section has also been completed.[50][44]
