Uttarkashi (Uttarakhand): Recommending future safety measures in the aftermath of the tragic incident at the under-construction Silkyara Bend–Barkot tunnel in Uttarkashi , experts have submitted a primary investigation report to the Union Ministry of Road Transport and Highways. The comprehensive report highlighted several critical factors contributing to the unfortunate accident that endangered the lives of 41 labourers on November 12.
The investigation, conducted by a six-member central team between December 13 and 15, meticulously scrutinized the incident's causes, revealing alarming deficiencies in the construction process. The report pointed out the selection of an incorrect alignment in a shear zone, a lack of adequate safety measure during re-profiling and a failure to learn from past accidents as primary reasons behind the mishap.
One of the striking revelations of the report was the absence of essential sensors and equipment inside the tunnel. These crucial instruments, responsible for monitoring ground behaviour during re-profiling, were found to be insufficient, hampering the timely implementation of necessary precautions. Furthermore, the construction company reportedly operated without proper authorization for their working methods from the authorized engineer appointed by the executing agency NHIDCL.
Inadequate monitoring by NHIDCL (National Highways & Infrastructure Development Corporation Limited) officials during tunnel construction emerged as a concerning issue flagged in the report. The incident, which occurred on November 12 due to a landslide in the tunnel, exposed critical lapses in the construction process.
Despite the necessity for re-profiling in the tunnel, a proper support system was not promptly provided after excavation, leading to precarious conditions exacerbated by the use of rebar ribs instead of garter ribs in the landslide-prone area.
Explaining the significance of shear zones (a significant structural feature and represent deformation markers in orogenic belts). They are the places of preferred accommodation of deformation and the relative movement between the crustal blocks in both Phanerozoic and Proterozoic orogens.
Dr Sushil Kumar, a retired geoscientist from the Wadia Himalayan Institute of Geology, emphasized the need for extra precautions during construction in these sensitive rock areas. He highlighted the necessity of proper treatment and packing while excavating in shear zones to mitigate risks.
Shockingly, the report unveiled that the Silkyara Tunnel had experienced approximately 21 landslides prior to the tragic incident, underscoring a failure to learn from past occurrences. Despite these warning signs, the necessary lessons were not implemented, putting the lives of workers in peril. To avert such catastrophes in the future, the investigation report has strongly recommended establishing a dedicated tunnel centre for roads and railways.
An emphasis has been placed on developing a new Standard Operating Procedure (SOP) for tunnel safety and creating a collaborative geological platform specifically tailored for project construction, particularly in the Himalayan region. The report's findings underscore the critical need for stringent adherence to safety protocols and comprehensive measures to prevent similar accidents, emphasizing the urgency of implementing the recommendations to ensure the safety of future infrastructure projects.
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