Resilient Tunnelling in the Himalayas and Beyond: Lessons from Recent Projects

Abstract

The recent tunnel collapses at Silkyara (Uttarakhand, 2023) and SLBC Tunnel 1 (Telangana, 2025) have reshaped the way underground infrastructure projects are perceived and executed in India. While both incidents were tragic in scale and impact, they have provided critical insights into the gaps that exist in current tunnelling practices—particularly in geological investigations, risk anticipation, contract frameworks, and crisis response mechanisms.
This extended abstract analyses these two case studies not only from a technical standpoint, but also from the broader lens of resilient engineering. At Silkyara, the collapse during re-profiling exposed the underestimated complexity of a shear-dominated zone and led to a dramatic 17-day rescue mission. At SLBC, a sudden inflow of water and debris caused the submergence of a TBM, bringing to light the risks of advancing through shear zones with limited predictive confidence.
In both cases, the aftermath triggered a re-evaluation of excavation methods, safety protocols, and planning culture. The move from TBM to Drill and Blast (D and B) at SLBC, the application of real-time monitoring and GBRs at Silkyara, and the eventual incorporation of Aerial Electromagnetic (AEM) surveys reflect a transition toward adaptive, site-specific resilience in tunnel engineering.
The paper concludes by synthesising the lessons learnt into actionable engineering strategies and policy recommendations for future projects in the Himalayas and beyond. It proposes that true resilience lies not just in reacting to failure but in anticipating it—and designing systems robust enough to prevent it or recover from it swiftly.