Namma Metro Phase 3A Red Line: Hebbal to Sarjapur Bengaluru’s Costliest Metro Project Ever

Bengaluru is gearing up for a transformative addition to its metro network. Under Phase 3A of Namma Metro, the proposed Red Line will extend from Hebbal in the north to Sarjapur in the southeast, slicing through some of the city’s busiest tech hubs, residential belts, and high-density corridors.  

Why the Red Line is so ambitious (and expensive)

This corridor is being billed as BMRCL’s costliest venture yet, with a projected capex of ₹28,405 crore, which works out to roughly ₹776 crore per kilometer.  Several factors contribute to this premium:

• Underground stretch & tunnelling: Approximately 16.8 km of the route between Koramangala and Hebbal will be built underground, housing 11 stations in that stretch. The complexity of tunnelling through Bengaluru’s rocky geology escalates costs.  

• Elevated sections: The elevated segment from Sarjapur to Koramangala will include 15 stations.  

• Land acquisition costs: About 161.65 acres of land are required, including 55.69 acres of private land near Sarjapur Circle for a proposed depot. The acquisition bill alone is pegged at ₹8,080 crore.  

• Urban density & complexity: Nearly half the route traverses dense urban zones, requiring careful design, alignment, and mitigation of disruptions.  

• Inflation, regulatory shifts, and evolving design norms: As with many long-term infra projects, cost escalations over time are expected, especially when markets and material costs fluctuate.  

Timeline & approvals

• The Detailed Project Report (DPR) is currently under review by the Ministry of Housing and Urban Affairs (MoHUA). The union government has asked for a fresh reassessment of costs tied to underground construction before granting final approval.  

• The Karnataka state cabinet cleared the proposal in December 2024, but since the Centre holds 50 % equity in Namma Metro, final clearance depends on central concurrence.  

• Geotechnical investigations are underway: BMRCL has floated tenders worth ₹6.86 crore, with a deadline for bids, and a 150-day timeline for surveys post-award.  

• The targeted completion is December 2030, though delays to 2031 aren’t ruled out depending on approvals, execution pace, and on-ground challenges.  

Route & stations

The Red Line promises to connect major nodes across Bengaluru:

• It will cut through areas like Agara, Koramangala, Dairy Circle, Bellandur, St. John’s Hospital, NIMHANS, Central College, Cunningham Road, Mehkri Circle ensuring linkages across residential, commercial, health, and educational zones.  

• Of the total stations, 11 will lie underground (in the Koramangala–Hebbal stretch) and the rest elevated between Sarjapur and Koramangala.  

• Once operational, it will integrate with the existing metro network (Green, Purple, Yellow lines) and upcoming corridors Pink and Blue enhancing connectivity across the city.  

Challenges & outlook

• Cost rationalization: Given the scale of outlay, BMRCL and the central government must optimize design, procurement, and execution to prevent overruns.

• Engineering complexity: Bengaluru’s rock strata pose tunneling risks; soil tests and geotechnical assessments will be critical.

• Land & social impact: Negotiating with private landowners and managing resettlement will be sensitive and time consuming.

• Regulatory & intergovernmental coordination: Alignment between State, Central, and local agencies will be essential for permissions.

• Timeline certainty: While 2030 is the target, past infra projects show that such deadlines often stretch.

Even with its high cost, the Red Line has the potential to reshape mobility in Bengaluru especially along the Outer Ring Road corridor and dense tech zones. If executed well, it could become the backbone of urban transit in one of India’s fastest-growing cities.