Uttarakhand Tunnel Project and Silkyara Disaster

Despite housing a number of these, Uttarakhand tunnel projects are witnessing the heat of review, close scrutiny and critique from various ends including general public and media.

Global attention was suddenly drawn towards tunnels, tunnelling and hazards associated with it after the collapse of a portion of 4531 m long under construction Silkyara – Poulgoun – Barkot tunnel in Uttarakhand on 12 November 2023, as 41 workers were trapped therein.

Resources and expertise to plan and execute the rescue operations were drawn from across the country and intermittent success and failures in these attempts and media coverage of the efforts as also ordeal of the next of kin of the trapped persons made this operation emotionally charged and highly dramatic and the same concluded with rat-hole miners digging off the last hurdle and saving the trapped workers on 28 November 2023.

 

The World of Tunnels

Tunnels, the subterranean marvels that carve through mountains and traverse beneath waterways, have long been instrumental in shaping the landscape of connectivity and transportation across the world.

From ancient underground passageways to modern engineering marvels, tunnels have played a pivotal role in facilitating travel, trade, and infrastructure development. Nowhere is their significance more pronounced than in hilly regions, where these provide vital connections, bypass surface hazards, and unlock the potential for economic growth and societal advancement.

The Evolution of Tunnels

The history of tunnelling dates back millennia, with early civilizations carving rudimentary tunnels for irrigation, defence, and religious purposes. The ingenuity of ancient tunnel builders of the Euphrates and other places laid the foundation for the development of more sophisticated tunnelling techniques, culminating in the construction of iconic tunnels that have stood the test of time. The evolution of tunnelling reflects humanity’s unwavering quest to conquer geographical barriers and harness the earth’s subterranean realm.

The world is adorned with a tapestry of major tunnels, each a testament to human ingenuity and perseverance. From the iconic Gotthard Base Tunnel in Switzerland, the world’s longest and deepest rail tunnel, to the transformative impact of the Channel Tunnel linking the United Kingdom and France, these engineering marvels have redefined the possibilities of cross-border connectivity and trade.

The benefits of major tunnels are manifold, encompassing enhanced transportation efficiency, reduced travel times, and the mitigation of environmental impact by diverting traffic away from ecologically sensitive surface areas.

Tunnels in Hilly Regions

In the hilly regions, where rugged terrain and natural obstacles pose formidable challenges to surface transportation, tunnels emerge as indispensable conduits of connectivity. By burrowing through mountains and bypassing treacherous terrain, tunnels provide vital links that enhance accessibility, foster regional integration, and bolster resilience against environmental hazards.

In these regions, tunnels serve as lifelines, enabling the seamless flow of goods, services, and human traffic, thereby catalyzing economic development and enhancing the quality of life for local communities.

It is therefore no surprise that many sections of the Char Dham Yatra route as also Rishikesh – Karnnprayag railway in Uttarakhand are planned to traverse through tunnels.

Hazards in Tunneling

Silkyara tunnel collapse has brought forth the hazards associated with tunnelling together with complications likely to be encountered in rescue operations and therefore it becomes pertinent to review these hazards that emanate from associated underlying reasons, which are discussed below.

Geological Instability: The presence of unstable rock formations, and geological discontinuities as also weaknesses often result in collapse, rockfall, and ground subsidence, that have the potential of posing serious risk to workers as also structural integrity of the tunnel.

Fire Emergencies: The confined nature of tunnels can exacerbate the impact of fires, resulting in rapid spread, smoke accumulation, and challenges in evacuation. Fire emergencies in tunnels require robust fire detection, suppression, and evacuation systems to ensure the safety of occupants.

Water Ingress and Flooding: Tunnels located in water-bearing strata or areas prone to flooding are at risk of water ingress, which can compromise structural stability, damage to  electrical systems, and pose drowning hazard to workers and occupants.

Air Quality and Ventilation: Poor air quality due to vehicle emissions, construction activities, or natural gases can create hazardous conditions within tunnels, necessitating effective ventilation systems to maintain breathable air and mitigate the risk of asphyxiation or exposure to toxic fumes.

Construction and Excavation Risks: Traditional excavation methods, such as drilling and blasting, can introduce risk of rockfall, collapse, and worker injuries. Advanced construction techniques, including tunnel boring machines (TBMs), aim to mitigate these risks through mechanised and controlled excavation.

Notable Tunnel Disasters

Though providing ease of travel, tunnels have also been associated with major tragedies of which Mont Blanc Tunnel disaster in France is an example. It was on March 24, 1999 that a truck caught fire inside this tunnel resulting in a catastrophic blaze that caused tragic loss of 39 human lives. The fire, which burned for over 50 hours, caused extensive damage to the tunnel infrastructure and led to its closure for three years.

It was fire and truck again on May 29, 1999 – a truck caught fire inside the Tauern Tunnel in Austria, resulting in a massive blaze that claimed 12 lives.

Then on September 11, 2008 a freight train caught fire in the Channel Tunnel connecting the UK and France. There were however no fatalities in this incidence.

An under construction Yerba Buena Island tunnel in USA collapsed on 1 March, 1999 resulting in tragic loss of 03 workers.

All these tunnel related incidences highlight the risks associated with tunnel construction and importance of stringent safety protocols together with the importance of robust safety measures and emergency response protocols in tunnel operations that include effective ventilation systems, stringent fire safety standards, and comprehensive training for tunnel personnel to handle crisis situations.

Mitigation Measures for Tunnel Related Risks

To mitigate the risk of tunnel related hazards, a comprehensive approach to safety is essential.

Meticulous Planning and Geological Surveys: Before the commencement of tunnel construction, meticulous planning and comprehensive geological surveys are essential. These surveys help in assessing the stability of the surrounding rock and soil, identifying potential geological hazards, and determining the most suitable construction methodology.

Advanced Construction Techniques: The use of advanced construction techniques, such as tunnel boring machines (TBMs) and reinforced concrete linings, is vital to ensure the structural integrity of the tunnel. These help in minimizing the risks associated with traditional excavation and construction processes.

Maintenance and Inspections: Regular and thorough inspections using state-of-the-art technology are crucial for identifying any signs of structural weaknesses, water ingress, or other potential hazards. Ongoing maintenance, including structural repairs and reinforcement, is essential to uphold the integrity of the tunnel over its operational lifespan.

Emergency Response Plans and Training of Personnel: The development of robust emergency response plans and the training of personnel for prompt and effective action in crisis scenarios are imperative pillars of tunnel safety. Personnel need to be well-prepared at all times to immediately respond to emergencies, including fires, collapses, or other unforeseen events, through regular drills and scenario-based mock exercises.

Ventilation and Fire Safety Systems: Effective ventilation systems and stringent fire safety standards are critical for ensuring the safety of tunnel users and workers. Proper ventilation helps in maintaining air quality and managing potential hazards, while robust fire safety systems are essential for preventing and containing fires within the tunnel environment.

Collaborative Efforts and Best Practices: Collaboration among government agencies, engineering firms, construction companies, and emergency response teams is essential for fostering a culture of safety and preparedness. Sharing best practices, lessons learned from previous incidences, and technological advancements can significantly enhance the overall safety and resilience of tunnel infrastructure.

By implementing these comprehensive safety measures, the risks associated with tunnel construction and operation can be effectively mitigated, ensuring the safety of workers, passengers, and the infrastructure itself.

United for Safety and Way Forward

The successful rescue of the workers in Silkyara exemplifies the power of collaborative efforts as diverse stakeholders from across the country converged in a synchronized display of solidarity and expertise and resources were successfully orchestrated  to rescue the trapped workers.

This exemplifies the significance of effective coordination, clear communication, and the mobilization of resources at the face of adversity.

One thing though recommended after every single disaster but seldom done, related to systematically document the challenges faced in this operation and methodology adopted to overcome the same. As this aspect relates to individuals coming in from different places, in the absence of formal debriefing, the experiences remain confined to the individuals and never utilised institutionally.

It is therefore required that the practice of debriefing and documentation of experiences be institutionalised for all disaster related operations. 

As resources were mobilised from different agencies it is necessary to prepare an inventory of resources, technologies, and expert manpower available with different agencies together with the details of the contact persons of these agencies for requisitioning these. This would same time and effort during similar incidences in times to come.

Rather than reviewing the safety measures provided in the tunnel just for the purpose of fixing accountability for the accident it is warranted that comprehensive guidelines for ensuring safety be prepared in consultation with various stakeholders and mechanism be put in place for strict compliance of the laid down measures, with provision strict action against defaulters.