Overview of the Silkayara Tunnel and Recent Incident

The Silkayara Tunnel, situated in the picturesque valleys of Uttarakhand, gained national and international attention in recent weeks due to a collapse caused by surface loss and rock deformation. Connecting Dharasu to Yamunotri along National Highway 134, this 4.5-kilometer tunnel was under construction by Navayuga Engineering Construction Limited (NECL).

History and Purpose of the Project or Why this project is Important

Let us try to understand the basics of Silkyara Tunnel. This tunnel is a part of the Chardham Mahamarg project launched by the Ministry of Road Transport and Highways (MoRTH). In March 2018, a budget of Rs. Rs 1383 crore was sanctioned for the construction of 4.531 km long two-lane bi-directional tunnel at Silkyara. The objective of the project was to connect Gangotri and Yamunotri axis under Radi Pass in Uttarakhand.

The tunnel was envisioned to reduce the snow-affected length of NH-134 (Dharasu-Barkot-Yamunotri Road) from 25.6 km to 4.531 km, provide all-weather connectivity and reduce travel time by 50 minutes. Can be done in 5 minutes.

NHIDCL (National Highways & Infrastructure Development Corporation Limited) signed a contract with Navyuga Engineering Pvt Ltd (NECL) for approximately Rs. 853.79 Crore on June 14, 2018. Although the work commenced on July 9, 2018, the project faced delays, with the current progress at 56%. The completion date is expected to be around May 14, 2024.

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Incident Details At silkyara – Barkot Tunnel

On November 12, 2023, at 05:30 hrs, a collapse occurred 205m to 260m inside the tunnel from the Silkyara portal, trapping 41 workers. Immediate rescue efforts began, involving state agencies Indian Army / State Disaster Response Force (SDRF)/ National Disaster Response Force (NDRF), (MoRTH) Ministry of Road Transport & Highways /NHIDCL/(NHAI) National Highway Authority of India /(BRO) Border Road organisation and other state departments. Coordination efforts included supplying fresh air, oxygen, water, electricity, and food to the trapped workers.

Various measures were taken for early evacuation, including excavation with shotcreting, additional shotcrete machine deployment, and the involvement of geotechnical and geological experts. The removal of loose debris and the introduction of a 900 mm dia MS Steel Pipe with a Hydraulic Jack were also initiated.

All coordinated efforts are being made to evacuate the stranded workforce at the earliest, with continuous monitoring and assessment by experts and authorities.

Silkayara Tunnel Topography Important for the Geotechnical Engineer  
The Silkyara Tunnel is located in the Himalayan Mountain range, an area known for its unstable topography due to the ongoing collision of the Indian and Eurasian tectonic plates. This instability poses a significant challenge to tunnel construction.

latest interview with the director of NECL, he mentioned that the tunnel collapse was not a new occurrence. Still, this time, the incident gained attention due to the workers stuck inside the tunnel

Let’s look the specifics, The Silkyara Tunnel is being constructed through a layer of quartzite rock. Quartzite is a hard rock resistant to weathering and erosion. However, it can be brittle and susceptible to fracturing.

Note: It’s absolutely crucial to follow strict standard procedures during any construction. Opting for shortcuts is not just about financial losses; it directly jeopardizes human safety. Ignoring these protocols is not only reckless but potentially disastrous. Ensure adherence to procedures for everyone’s sake.

What is the important thing that we can learn from this incident?

“Well, it is very important during any construction to follow the basic norms, especially for safety procedures. Construction projects entail not only monetary losses but also the potential for human loss if a single mistake is made. The planning phase is crucial, and the implementation is equally challenging, as various examples have shown.

Specifically, if we talk about the basic standard norms that were not followed at the Silkayara Tunnel:

1. The safety route was not prepared, though it was planned during the tunnel’s planning phase but not implemented.

As per the Standard Operating Procedure (SOP), it is mandatory to develop an escape plan or safety route for use during an emergency. In line with Indian standard procedures, it is emphasized that the construction of emergency or safety routes is important for tunnels longer than 3 km. Initially, during the planning phase, a route was prepared, but unfortunately, it was not implemented during subsequent site visits or investigations. This oversight reflects a significant mistake and failure on the part of the organization.

As safety measures are crucial on construction sites, whether it involves building construction, bridge construction, or tunnel construction, adherence to standard norms is of utmost importance at every site. Alongside, meticulous planning is necessary for each project. As engineers or leaders of projects, it is our responsibility to consider every small detail and ensure the implementation of proper safety instructions on the site. This not only prioritizes the well-being of the workers but also contributes to cost savings for the project. By following safety protocols and guidelines, we can guarantee a secure and efficient construction process