Silkyara-Barkot tunnel collapse in Uttarakhand shows overhaul must in infra works, says report

Neeraj Mohan

New Delhi, January 30

The collapse of the Silkyara-Barkot tunnel in Uttarakhand last year has unveiled critical issues in tunnel construction in the Himalayan geology and emergency response plans, according to an investigation report of the Uttarakhand State Disaster Management Authority (USDMA). The investigation identified substantial shortcomings in the design project report (DPR), citing a lack of detailed geotechnical and geophysical investigation. The report advocates for future projects to prioritise comprehensive site studies, minimising unforeseen geological challenges. Furthermore, it points to the inadequacy of boreholes during the DPR stage, proposing more exploratory boreholes to reduce risks.

Shortcomings

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• A probe report has identified substantial shortcomings in the design project report, citing a lack of detailed geotechnical and geophysical investigation.
• A section of the Silkyara tunnel in Uttarkashi had caved in on November 12 last year. The 41 trapped workers were rescued on November 28.

The report reveals a collapse zone approximately 200 meters from the tunnel portal, characterised by a shear zone in the rock, indicating vulnerability in that specific geological formation. While the report doesn’t pinpoint specific reasons for the collapse, it underscores the need for a holistic approach to address challenges associated with tunnel collapses in the Indian Himalayas.

The unique geological composition of the region necessitates improved planning, construction practices and ongoing maintenance. The report proposes recommendations to address gaps identified in the Silkyara tunnel project, enhance safety measures and guide future tunnel constructions in challenging geological conditions.

To comprehensively understand future risk mitigation and improve preparedness tor tunnel rescue operation methods, the report recommends the constitution of a technical advisory committee comprising experts from the Geological Survey of India and other technical agencies.