Appraisal of Rescue Operations in Silkyara Tunnel by Maj Gen AK Chaturvedi (R)



It is a 4531mtr long tunnel enroute to Yamunotri which will reduce the distance to Yamunotri by 26 km and in terms of time by 45 minutes. Once completed it will be a single tube tunnel . It would feature two lanes separated by a vertical partition wall. Its diameter would be 15 meters. This area has extremely weak rock mass comprising of meta silt stone and phyllites. Collapse had happened at chainage 206 metres extending up to chainage 260 metres towards the Barkot on 12 Nov 2023 at around 0530h in the morning. It also needs to be noted that the tunnel digging had got completed for about 2500 mitres and starting from Silkyara only 200 mitres of concrete lining had been done.

Some Relevant Details of the Rescue Operation

  1. Time taken- 422 h over 17 days
  2. Workers- over all 1000 pers including over 600 of the govt agencies and the number of agencies about 18.
  3. Approach- Whole of Nations approach

Tasking of various agencies

  1. PMO- Monitoring.
  2. MoRTH and ministry of civil aviation- Coordination with other organs of the govt and external agencies.
  3. State Govt- Medical facility within the tunnel including a six bedded hospital, a 41 bedded hospital at Chingali Soth & provision of medicines and medical advice to trapped workers; initially through pipe & later through video, Logistics, Traffic control, safety and security.
  4. NDMA- Media interaction.
  5. NDRF and SDRF- Rescue and relief.
  6. BRO- Track construction of 1.1 km for taking machinery for vertical drilling, helping ONGC/ THDC for mining from Barkot side including track construction of 4.5 km, coordinating equipment transportation of American earth auger from Delhi to DEHRADUN and there to Silkyara. They also facilitated transportation of Plasma cutter from DRDO Hyderabad to the Tunnel site. Besides providing advice on operations to executive agencies they also provided 50 box-type culverts, 50 Hume pipes, a Remotely Operated Vehicle, a trenchless boring machine and  72mtrs of 800/700 mm MS Pipes for the construction of an escape tunnel.
  7. Army Engineers- Stand bye for Drift tunnels, innovations to support rat mining and cutting and welding, wherever necessary.
  8. Air Force- provision of Chinook for Cas Evac at Chingali Soth and transportation of equipment ex Indore and Hyderabad.
  9. SJVNL- Vertical drilling- 1200 mm hole.
  10. RVNL- Smaller hole of 6 inches from top.
  11. ONGC- Drilling from Barkot side for which advice and track was provided by BRO.
  12. THDC- For digging of tunnel.
  13. Navyuga Engineering- all operations of drilling being EPC contractor for this project of NHIDCL.
  14. Trenchless Services and Rockwell for the provision of Rat miners who drilled a hole of 12 meters and with the help of 201 Engr Regt pushed the pipe of 800 mm
  15. NHIDCL- Project Management and the agency responsible for the tunnel construction.
  16. International experts from Australia Arnold Dix & others from Norway & Thailand, Lt Gen Harpal Singh, Former DGBR, CE Central Command, Officials of MoRTH, and the State Govt. PMO remained in constant touch with the progress of the relief operations.

Time Lines

12 Nov – Collapse. Use of pipe to supply compressed oxygen used to provide dry fruit and fluids.

13 Nov- clearance and simultaneous concreting attempted- did not work.

14 Nov-smaller drill and earth-moving equipment were used to clear the debris- not much of a success. Work had to be stopped as some sounds were heard of stone cracking.

15 Nov- American auger reaches the site.

16 Nov- pipe inserted but the situation became grim as pipe insertions were not making progress. A minor earth quake experienced.

17 Nov-Auger hit Rock at 24 meters

18 Nov-planning to drill from five directions- vertical, horizonal (drift tunnelling) and creating an opening from Barkot side.

19 Nov- Drilling from the top commenced

20 Nov- 6-inch pipe inserted to provide hot meals.

21 Nov- Camera became functional.

22 Nov- Only 6 metres of drilling done.

23 Nov- Auger hits iron girder.

24 Nov- Drilling resumes but stops after 1.8 meters. It had by now reached 48 metres. The blades of auger were stuck so badly that the machine had to be removed. It was indeed a difficult task as it had to be cut and pulled out. Work commenced but it had its challenges.

25 Nov- Manual removal of debris commences from personnel of Jal board and Gorakhpur.

26 Nov- Work of earth continues.

27 Nov- Rat hole miners commence ops. It was a desperate move as Rat mining has been banned since 2014 under the provisions of NGT Act -2014. It may be noted that the Rate Miners work in a team of six, rotating among themselves tasks of digging, and removal of debris. The equipment used is a normal pick, axe, shovel and Hilti machine.

28 Nov- Crucial breakthrough is made after 12 metres of tunnel is dug by the rat miners in 24 h. In last two meters, challenges of falling debris are experienced but finally by 0715 h contact was established and evacuation commenced thereafter.


  1. As mentioned in an earlier article on the subject an Inquiry to pinpoint the responsibility has been ordered by the State of Uttarakhand.
  2. Has been a Safety audit of all tunnels ordered by the MoRTH.


  1. Probability of Post-Traumatic Stress Disorder among the trapped workers- The junior leadership took care of it by making the trapped workers follow a healthy routine, the medical authorities engaging with the trapped workers on a regular basis and the state administration making sure that hot meals and communication facilities are provided to the trapped workers.
  2. Multiplicity of control- Although, monitoring was being done at the highest level but a mechanism needs to be developed for such situations.
  3. Role of BRO- BRO is building 10 tunnels whereas NHIDCL is constructing 3 tunnels. Here it needs to be noted that BRO has a good safety record whereas NHIDCL is a fledgling organisation where due to short tenure of the leadership domain expertise is still not fully settled.- Need for more cross fertilization of knowledge between BRO and NHIDCL.
  4. DPR/ Construction methodology/ final ground-based survey- although, the ordered inquiry will bring out the failures, but as an initial observation all these aspects needs to be again revisited to ascertain whether certain shortcuts were taken in these areas.
  5. Environment Impact assessment- the question needs to be answered as to why it was not done.
  6. Why Escape tunnel which is mandatory for tunnels above 1.5 metres was not constructed?
  7. Rights of workers- applicability of Min Wages Act-1948, Employees State Insurance act-1948, Mines Act -1952, Employees Provident Act 1952. Here it needs to be noted that the emoluments of BRO workers is linked to altitude and it is well above the circle rate. Also, the compensation liability of the construction agency is higher in the case of BRO- It needs to be standardised and not left to the discretion of the agency.
  8. Limitation of equipment of foreign origin due to typical geological conditions of the Himalayas- need for developing indigenous industrial capability and also Capacity to handle that equipment.
  9. Use of animals to ascertain the profile of debris be thought of as RADARs available for this purpose have their limitations.
  10. Strength of Workers- frugality, Joint family system in villages, faith, commitment to fellow workers- it needs to be leveraged.


It is important to realise that the rescue operations concluded because of the strong will of the leadership, free hand to agencies involved in the operations, and continuous dialogue between decision makers and the technical team. It also highlighted the strength of the social fabric of Indian society which quickly comes together in times of crisis, without getting influenced by any kind of false narrative that the detractors attempt to build.

The collapse and the consequent rescue work also have suggested that it is important to be cautious rather than being reckless while working in difficult conditions. Additional time spent in planning and preparation definitely helps in safe and speedy construction. In this connection, we need to be cognizant of the fact that Himalayan Mountains are fragile and as such we need to be careful during the construction and if ever we violate the mandatory requirements like soil stabilization, Environment Impact Assessment, construction of escape tunnel and leaving lining of a drilled portion of the tunnel, it will all result into bigger trouble.

Finally, we as a nation need to realise that our terrain is unique, our problems are unique and the strength of our workforce is different. Thus there is a need to go for indigenous solutions rather than depending on foreign advice. Also, indigenous production of equipment needs to be given a boost to ensure that we do not depend on imported equipment, which will always have limitations due to typical Indian working conditions.

Watch Defence Dialogues: EP 89

Author – Maj Gen AK Chaturvedi, AVSM, VSM (Retd)  is a retired Indian Army General Officer who has served in Jammu & Kashmir, NE, Andman Nikobar on various appointments at Command and Army HQs. He is Vice Chairman of the Think Tank, “STRIVE”, and after retirement is pursuing his favourite hobby of writing for newspapers, journals, and think tanks.

Disclaimer: The views expressed are those of the author and do not necessarily represent the views of the organisation that he belongs to or of the STRIVE.