By Colonel Prashant Kumar Oberoi, Director, HS&PR, Border Roads Organisation
In November 2023, a section of the Silkyara-Barkot tunnel in Uttarakhand collapsed, trapping 41 workers and leading to a 17-day ordeal. A multi-agency rescue mission ensued, wherein the Border Roads Organisation (BRO) made a well-coordinated effort to free the trapped workers. Its tunnelling expertise and constant coordination with experts from various fields, coupled with grit and a spirit of solidarity, helped achieve the breakthrough in the operation. Additionally, being the nodal agency, the authority played an active role in facilitating the transportation of equipment.
Tunnel specifications
The Silkyara Tunnel is being built by National Highways and Infrastructure Development Corporation Limited (NHIDCL) on the Yamunotri National Highway connecting Silkyara to Barkot. This 4,531 metre long tunnel will reduce the road distance by 26 km and the travel time by 45 minutes. It is designed as a single-tube tunnel with two lanes divided by a vertical partition wall. The tunnel is being constructed in an extremely weak rock mass constituting meta-siltstone and phyllites. The 15 metre diameter of the tunnel makes its construction technically intricate. The collapse occurred between chainage 206 metre at the Silkyara end and spread to chainage 260 towards the Barkot end.
Heading the rescue operation
The BRO was made the nodal agency to coordinate among the various agencies that were involved in the operations to rescue the trapped workers. The agencies included the Indian Army, the BRO, the National Disaster Response Fund (NDRF), the State Disaster Response Fund (SDRF), NHIDCL, the Oil and Natural Gas Corporation (ONGC), Rail Vikas Nigam Limited (RVNL), SJVN Limited, and Tehri Hydro Development Corporation (THDC). The BRO was instrumental in giving valuable inputs based on its tunnelling experience when various rescue options were being discussed and finalised.
It was involved in the planning and execution of the side draught near the site. Another important task that it was entrusted with was the transportation of the American auger machine to the site. It coordinated its movement from Delhi to Dehradun and to the site at Silkyara, and ensured it became functional at the site by November 15, 2023. The BRO also coordinated the movement of equipment, such as drill machines, pipes of various sizes and remotely operated vehicles (ROVs) belonging to various agencies, by interacting with the Air Force, the civil aviation ministry, and various other central and state government agencies.
Damage control
The major rescue operation was carried out using the American auger machine along the Silkyara end. This approach involved a horizontal 900 mm pipe being inserted through the 60 metre collapse zone using the American auger machine. This machine was placed on site immediately as the first response, moved by the logistics team stationed in Dehradun, and started operations by November 15, 2023. The auger progressed 47 metres across the collapse zone but got stuck on November 24, 2023. The BRO team facilitating logistics got into action and transported a plasma-cutting machine from the Defence Research and Development Organisation (DRDO), Hyderabad, to the site. The auger was removed by cutting. The balance section was excavated manually. A team of army engineers assisted the rescue operations.
Examining the best course of action
There were four more options being exercised to increase the probability of success. The first approach was a vertical drill of 1.2 metre diameter, planned from the top of the hill by SJVNL. The drill hole was planned at chainage 306 metre from the Silkyara end. For this task, the BRO was asked to recce and provide a 1,150 metre approach road to the drilling site. It did so against all odds within 48 hours and also assisted SJVNL in getting its drilling equipment to the site on November 25, 2023.
In another option, ONGC planned a vertical drilling from the Barkot end for which equipment was mobilised. The drill hole was to be 323 metres deep with a finished diameter of 16 inches. For this approach, the BRO was asked to provide a track up to the drilling site. It surveyed a track of 4.5-5 km. The equipment for construction of this track was moved in haste. However, before this task could have been undertaken, the rescue was successfully carried out.
For the rescue personnel working inside the tunnel, a safe passage was required in case of any calamity. To this end, the BRO provided 50 box culverts and 50 metres of hume pipes. The same equipment was used to create a safe passage inside.
Combined efforts
The BRO also provided operational logistics to the rescue teams. To this end, it coordinated from the headquarters of the Directorate General Border Roads (DGBR) in Delhi, and Dehradun airport. These teams were tasked to coordinate with the central/state government agencies for ensuring uninterrupted/unhindered supply of critical equipment received from various parts of the country to the tunnel site to facilitate timely rescue. Due to the plethora of agencies involved, the team coordinated with 12 Air Force stations, the Airports Authority of India (AAI), the DRDO, ONGC, the National Technical Research Organisation (NTRO), the Central Industrial Security Force (CISF), the Uttarakhand State Disaster Management Authority (USDMA), and state civil administration and police for the provision of a green route. In addition to the most critical American earth auger machine with 18 augers that were moved on priority, the BRO logistics team was instrumental in moving other critical equipment such as the DRDO’s ROVs, trenchless mini tunnel boring machines, 12X MS iron pipes of 800/700 mm diameter and a total length of 72 metres, which were critical for constructing the horizontal escape tunnel, and plasma-cutting machines at the site in coordination with other stakeholders. Besides critical equipment, technical manpower was transported for the operation, ensuring it reached the rescue site in the fastest time frame. This included critical welders, who were moved during the night to the site.
The BRO’s road construction, maintenance and tunnelling equipment was deployed at the site to provide support to NHIDCL. It kept the approach road to the site, the Rishikesh-Dharasu Bend Road, operational at all times with its quick reaction maintenance teams working round the clock. The DGBR also visited the site and reviewed the rescue operations being carried out by the integrated team of committed workers from various organisations with a singular aim of saving 41 precious lives.
Ensuring worker safety
The BRO was instrumental in not only catering to critical logistics requirements and coordinating this challenging rescue operation, but also in creating the much-needed approach tracks at critical junctures of the operation, thereby providing the much-needed mobility for the drilling equipment of various agencies. The BRO has always been at the forefront in creating and maintaining the infrastructure along the country’s borders and is also the first responder in a crisis, working silently to achieve the common goal of saving precious lives in calamities, as could be seen in both Sikkim and at the Silkyara Tunnel in Uttarakhand.
