Hosur–Bommasandra interstate metro project hits roadblock due to technical incompatibility

Hosur–Bommasandra interstate metro: The ambitious Tamil Nadu government proposal to build South India’s first interstate metro line connecting Hosur with Bengaluru has hit a major roadblock, with the project now deemed technically unfeasible.

According to the Bangalore Metro Rail Corporation Limited (BMRCL), the Hosur–Bommasandra corridor cannot be integrated with the Bengaluru metro system because the two states use completely different power traction technologies.

The Tamil Nadu metro system runs on 25 kV AC overhead traction, while Bengaluru’s Namma Metro operates on 750 V DC third-rail traction.

The Chennai Metro Rail Limited (CMRL) had earlier proposed a feasibility study for a 23-km metro corridor linking Hosur, an industrial hub in Tamil Nadu, with Bommasandra in Bengaluru. However, BMRCL has now conveyed to the Karnataka government that such an integration is technically impractical.

Meanwhile, BMRCL has undertaken its own feasibility study to extend the existing Bommasandra metro line up to Attibele — the last suburb on the Karnataka side before the Tamil Nadu border. The proposed 11-km stretch will use the same 750 V DC traction system as the rest of the Bengaluru metro network.

“We have shared our opinion with the state government. The final decision will be taken by the government,” said a senior BMRCL official. The Tamil Nadu government had pitched the Hosur-Bommasandra metro link as part of its larger effort to develop Hosur as a major industrial township.

However, the proposal had met with strong resistance in Karnataka, where critics argued that the project would benefit Hosur far more than Bengaluru while adding additional traffic and operational burdens to the city’s infrastructure.

According to the initial plan, two stations were to be constructed 300 meters apart on either side of the inter-state border, with a pedestrian skywalk linking them. But BMRCL officials now say that such an arrangement is “technically impractical and operationally unviable.”

Multiple expansion plans for Bengaluru metro:

While the interstate link may be shelved, BMRCL is already pursuing several other expansion projects within Karnataka. These include:

Extension of the Blue Line from Dodjala to Devanahalli.

Extension of the Purple Line from KR Puram to Hoskote.

Extension of the Silver Line from Kadabagere to Tavarekere.

A new 68-km corridor from Kalena Agrahara to Bannerghatta, Jigani, Attibele, Sarjapur, Dommasandra, and Varthur Kodi, ending at Kadugodi Tree Park.

Officials said that the Union Ministry of Housing and Urban Affairs has directed BMRCL to prepare a master plan to expand Bengaluru’s metro network to 470 km, comparable to Delhi’s metro system.

With seven extensions and new corridors under consideration, Bengaluru’s metro network is expected to reach 467.69 km — nearly matching the Delhi-NCR metro’s planned 467 km network.

If realized, this expansion would make Namma Metro one of the largest urban rail systems in India, although the long-discussed interstate link with Hosur now appears unlikely to materialize.

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