‘Tunnel Road will take away six acres of Lalbagh land, damage the ecosystem’

The proposed 16.7 km Tunnel Road Project between Hebbal and Silk Board is now drawing criticism for its potential to cause irreversible damage to Bengaluru’s largest lung space, Lalbagh Botanical Garden.

Apart from taking away almost six acres of Lalbagh land, the project has high potential to damage the entire ecosystem, since the likelihood of irreversible and unacceptable harm is high, activists, including Rajkumar Dugar from Citizens for Citizens (C4C) and others from Bangalore Environment Trust (BET), who made a report on Bengaluru’s Tunnel Road Project and Lalbagh, said. 

Pointing to the detailed project report (DPR), they said that the project will pass beneath Lalbagh for 700 m with two 50-foot-wide tunnels running 50 to 100 ft. below ground, along with two long ramps and a massive ventilation shaft. Around 23,800 sq. meters or nearly six acres of Lalbagh land along the 1.1 km Siddapura Road stretch between Ashoka Pillar and Marigowda Junction will be acquired. A 1.4 km entry ramp will start about 50 m from the Ashoka Pillar, while a 1.1 km exit ramp will emerge near Marigowda Junction.  These will facilitate vehicle movement mainly from Shantinagar, Wilson Garden, Dairy Circle, and Jayanagar towards Hebbal, but not in the opposite direction. Activists warn the project will choke the area with gridlocks, air and noise pollution, and a host of long-term environmental hazards.

“Among the gravest concerns is the fate of the 3-billion-year-old Lalbagh Rock, one of the oldest exposed rocks on Earth, declared a National Geological Monument by the Geological Survey of India (GSI) in 1975. The 16th-century Kempegowda watchtower standing atop it marks Bengaluru’s early boundary,” Mr. Dugar said, pointing out that the project proposes to bore two 15 m tunnels and two 10 m ramps through this ancient formation using powerful tunnel boring machines, which could fracture the rock and destabilise the terrain.

Lalbagh Lake, spread over 40 acres, serves as a vital rainwater catchment and biodiversity hotspot, home to fish, amphibians, reptiles, and migratory birds. The tunnel entry ramp from Ashoka Pillar passes less than 100 ft. from its edge, Mr. Dugar mentioned, adding that tunnelling could disrupt underground water channels feeding the lake, leading to flooding, drying, or contamination, threatening its aquatic life and delicate microclimate.

Activists further note that beneath the surface, tunnelling could severely alter aquifers that sustain nearby wells, borewells, and interconnected lakes, and that continuous water seepage into tunnels could drain fractured-rock aquifers, while construction chemicals might contaminate groundwater. Blocking percolation paths, they add, could deplete recharge zones and destabilize the soil.

“Lalbagh’s estimated 3,000 plant species, including many rare and heritage trees, face equal peril. Trees within the six acres earmarked for acquisition will have to be removed, though the DPR reportedly remains silent on the number. Roots damaged by excavation, vibration, and heavy machinery may weaken nearby trees, leading to long-term mortality. The loss of canopy and green cover within a designated botanical garden is the worst kind of developmental irony,” activists said.