NGRI nears completion of geophysical survey for SLBC tunnel project, 3D mapping to guide final phase

The NGRI is close to completing its helicopter-borne electromagnetic survey of the unfinished stretches of the SLBC Tunnel Project. A comprehensive 3D map with high-resolution visualisations will be submitted to the government by month-end, providing crucial data to resume construction.

Hyderabad: The helicopter-borne electromagnetic geophysical survey taken up on the incomplete stretches of the Srisailam Left Bank Canal Tunnel Project by the National Geophysical Research Institute (NGRI) is nearing completion.

The survey findings with a comprehensive 3D map are expected to be delivered to the government by the end of this month. NGRI officials confirmed that despite the extended timeline, the report to be supported with high-resolution 3D visualizations, will be finalized soon.

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It will provide the state with the critical data needed to accelerate construction of the leftover stretches of the SLBC tunnel project.

‘This is not just about mapping rock formations. It is more about the tunnel’s alignment minimizing risks while maximizing efficiency,” irrigation officials said.

The 3D model will help shape the critical final phase, blending precision engineering with real-time environmental safeguards, they added.

Spanning a total of 43.39 kilometres underground, the project has already covered 33.59 km using the Tunnel Boring Machine (TBM) technology. With 9.8 km left, the government’s revamped strategy intends to achieve its full completion within the next two years.

Under construction within the biodiversity hotspot of the Nallamala Tiger Reserve, the tunnel’s development has been a delicate balance of progress and preservation.

To fast-track the work on the project without encroaching on the adjacent Amrabad Tiger Reserve, officials plan to integrate controlled blasting methods with minimal vibrations and zero habitat disruption.

As the report reaches the government, the new plans will be unveiled for resuming work on the tunnel that was abandoned on February 22 this year, following the roof collapse killing two workers, while six others left missing inside the tunnel. A rescue mission that lasted for over two months failed to trace them.