Bengaluru: The Congress government's pet project of Bengaluru Tunnel Road project may have to go back to the drawing board over its plan to build the tunnel under road beneath Lalbagh, with Geological Survey of India (GI) expert committee report flagging a series of serious geological, structural and groundwater risks to the iconic botanical garden and the three-billion-year-old Lalbagh rock.
Also Watch:
The report, which was submitted to the government in April, the GSI committee has warned that the tunnelling and excavation could damage Lalbagh's ancient rock mass, widen existing cracks and threaten the Kempegowda tower, besides posing risks of the ground disturbance and groundwater level changes.
The tunnel road project has been in the eye of the storm since inception with Bengaluru South Member of Parliament Tejaswi Surya, along with a group of IISc scientists opposing the ₹22,267 crore project, fior which the Adani group has bagged the contract. The group has gone to the High Court against the project running up to 16.75 kms between Hebbal and Central Silk Board junction. The government was forced to withdraw the Park (Preservation) Amend Bill, 2026 after stiff public opposition, who alleged that the bill was brought to divert Lalbagh land for the tunnel road project.
The five member GSI committee has warned that the existing surface investigation provided in the detailed project report (DPR) of the tunnel road is inadequate given the geological setting of the area. The proposed Shaft 4 adjacent to the National Geological Monument is a `critical concern' and there is a need for an independent technical review of the location of the tunnel boring machine (TBM) Shaft 4, with the objective of maximising the distance from the geological monument (rock), the report recommended.
``Excavation for the TBM shaft using drill and blast method near the Lalbagh Geological Monument could induce rock fractures or destabilise parts of the formation. The hydrological impacts due to changes in the seepage paths within differing lithologies may also affect the Lalbagh lake and downstream areas,'' the report pointed out.
The report describes the Lalbagh stretch as a structural transition zone and the tunnel alignment passes through different varieties of granite and gneiss. The GSI has made five recommendations to the government, including to conduct comprehensive geo-technical investigations, and, if necessary, three dimensional geological modelling before proceeding with the project.
The GSI report has also acknowledged the representations made by civil society to nominate Lalbagh for the Unesco World Heritage site.
