As many as 6,868 trees will be affected by Namma Metro Phase 3, according to the project’s Environmental Impact Assessment (EIA) report, significantly lower than the earlier estimate of 11,137 trees. Of the affected trees, 65 per cent will be felled, 15 per cent transplanted and 20 per cent pruned.

For every tree felled, Bangalore Metro Rail Corporation Ltd (BMRCL) has committed to transplanting 10 saplings of native species at a cost of Rs 2,000 per sapling. The EIA notes that a heritage banyan tree with a girth of 2,700 cm and a canopy spread of 1,242 sq m—one of the city’s largest—will also be impacted, as highlighted in a separate study by Azim Premji University.

Phase 3 comprises two elevated corridors spanning 44.65 km. Corridor 1, measuring 32.2 km, will run from JP Nagar 4th Phase to Kempapura, while Corridor 2, at 12.45 km, will connect Hosahalli to Kadabagere along Magadi Road. Once completed, Phase 3 will expand Bengaluru’s metro network to 222.2 km, with the project currently slated for completion in May 2031.

Although the project has secured all statutory clearances, construction was delayed due to revised plans to build a 37.12-km double-decker metro-cum-road structure along the alignment. BMRCL plans to float tenders later this month, with construction expected to begin in June.

BMRCL said only trees that obstruct construction will be transplanted, felled or pruned, based on on-site verification by the Tree Expert Committee. Trees not designated for removal will not be damaged during construction. The corporation has also committed to monitoring the survival of transplanted trees and saplings for five years, replacing any that do not survive on an annual basis.

To mitigate environmental impact, BMRCL plans to plant native shrubs and groundcovers in medians beneath elevated sections to create green belts and improve streetscapes. Under compensatory afforestation, it will spend Rs 71.8 million along Corridor 1 and Rs 16.9 million along Corridor 2. Additional allocations of Rs 197 million and Rs 62.6 million, respectively, have been earmarked for environmental monitoring during construction.

Tree-cutting permission for Package 1 (JP Nagar–Mysuru Road) was granted in September 2025, and approvals for the entire project are expected by mid-2026. The EIA also notes potential impacts on the bonnet macaque, a vulnerable species listed on the IUCN Red List, for which a species-specific conservation plan has been prepared.

However, concerns have been raised by environmental groups. Dattatreya T Devare of the Bangalore Environment Trust said the EIA lacks sufficient detail on affected trees and alleged inadequate transparency, noting that public consultations were held in August and September without adequate information being shared in advance.