Mumbai’s mobility upgrade! India’s largest 13.34-m Single Shield TBM has been safely lowered for the Thane–Borivali Twin Tunnel project — the country’s biggest-diameter, longest urban tunnel

India’s biggest 13.34-metre Single Shield Tunnel Boring Machine has been safely lowered at the Thane portal, marking a historic milestone for the Thane–Borivali Twin Tunnel. This machine will carve out the country’s widest and longest urban road tunnel, setting the stage for one of Mumbai’s most transformative mobility upgrades.

With an estimated cost of around ₹20,000 crore, the Thane–Borivali Twin Tunnel is among India’s largest mobility investments. The project promises reduced travel time, lower pollution, and a future-ready transport link that will support Mumbai’s growth, ease congestion and reshape how the city moves for decades ahead.

The TBMs will advance at an average speed of 11 metres per day, boring through hills at a depth of around 60 metres. The engineering demands are immense—hard rock, uneven strata, and vibration control—but advanced technology is enabling safe, stable excavation beneath one of Mumbai’s busiest regions.

Once operational, the 11.8 km twin tunnel will cut the current 60–90-minute, 23-km commute between Thane and Borivli to just 15 minutes. This seamless underground link will remove traffic choke points, reduce fuel use, and reshape daily mobility for lakhs of commuters across the Mumbai Metropolitan Region.

The twin tunnel system spans 10.8 km, with 5.75 km being excavated from the Borivli side and 6.09 km from Thane. This deep underground route—approximately 23 metres below ground—creates Mumbai’s first large-scale, fully shielded cross-city link built entirely beneath a protected forest ecosystem.

The successful lowering of the cutter head on 29 November 2025 signals rapid progress for the ambitious Thane–Borivali Twin Tunnel. This project, led by MMRDA and executed by MEIL, will create a direct high-speed link between the eastern and western suburbs, significantly easing daily travel across Mumbai.

Four massive 13-metre Herrenknecht hard-rock TBMs will be deployed to bore through challenging terrain beneath SGNP. These high-precision machines minimise ground disturbance, enhance safety, and increase excavation speed, enabling engineers to deliver one of India’s most complex and eco-sensitive underground infrastructure projects efficiently.

Each tunnel will provide three lanes, including an emergency lane for quick response. Modern safety features—ventilation systems, fire-fighting units, cross-passages every 300 metres, smoke detection and LED guidance boards—will ensure smooth, secure and uninterrupted travel for motorists using this new high-speed corridor.

The tunnels pass beneath Sanjay Gandhi National Park, one of Mumbai’s most sensitive environmental zones. To safeguard wildlife, all drilling will be monitored by the Wildlife Institute of India. Advanced tunnelling technology ensures low vibration, minimal disturbance, and safe excavation deep under the protected forest landscape.

Work has accelerated after the monsoon. The Thane casting yard is operational, the Borivli casting yard is coming up, and land acquisition is nearly complete. Rehabilitation of affected families is progressing smoothly, allowing tunnelling preparations, material movement and final machinery placement to advance without delays.