3-Billion-Year-Old Lalbagh Rock Faces Tunnel Risk: GSI Flags Geological and Groundwater Concerns

Bengaluru: A major underground road proposal aimed at easing traffic has triggered a fresh debate over protection of one of Bengaluru’s oldest geological assets.

The Geological Survey of India has warned that the proposed 16.7-km Hebbal underground tunnel could affect the roughly three-billion-year-old Peninsular Gneiss formation inside Lalbagh Botanical Garden, according to a report placed before the Karnataka High Court.

Why the rock matters

The Lalbagh formation is not merely a prominent outcrop. It represents an extremely ancient chapter of Earth history, far predating human civilisation.

What could tunnelling change?

After examining the project report, the GSI flagged possible vibration and stress from shafts required for tunnel-boring machines, which could create or widen fractures in the rock mass.

The agency also raised concerns that tunnelling could lower the groundwater table or alter subsurface flow paths, with possible effects on Lalbagh Lake and nearby aquifers.

Development versus conservation?

The issue is not a simple choice between infrastructure and conservation. Bengaluru needs transport capacity, but ancient geological formations cannot be recreated once damaged. Geological risk, groundwater modelling and heritage-impact assessment therefore become critical in major urban projects.

Why Tumakuru should watch

For fast-growing cities such as Tumakuru, the controversy is a reminder that roads, industrial zones, rail projects and large construction schemes should account for groundwater, rock structure, lakes and local geology from the planning stage.

What next? Court scrutiny, the government response and any technical redesign of the project will determine the next stage.