Rs 16,621-crore Mumbai Coastal Road project gets major boost as TBMs clear factory tests

Mumbai’s Rs 16,621-crore Coastal Road North project is moving closer to its next major construction milestone, with two 15.6-metre-diameter tunnel boring machines (TBMs) expected to arrive in the city by January 2027. Tunnelling for the 3.9-km twin tunnels between Malad and Kandivali is scheduled to begin by May next year.

The Brihanmumbai Municipal Corporation (BMC) has completed the factory acceptance tests of the machines in Chennai, clearing an important step before their dismantling, transportation and assembly at the construction site.

The tunnels will connect Mindspace in Malad with Charkop in Kandivali, running approximately 40 metres below ground. They will form a key component of the 22.93-km Coastal Road North corridor, which will connect Versova with Dahisar, reported The Indian Express.

The BMC has appointed Megha Engineering and Infrastructures Limited (MEIL) to execute the tunnelling work, while Germany-based Herrenknecht is manufacturing the machines.

Each TBM will have a diameter of 15.6 metres, making them among the largest machines of their kind to be deployed in India.

The corporation has opted for mixshield slurry TBMs because the proposed tunnel alignment passes close to creeks and mangrove areas, where unstable soil conditions and groundwater ingress pose significant engineering challenges.

Unlike conventional machines used in hard-rock conditions, slurry TBMs maintain pressure at the excavation face to prevent surrounding soil from collapsing and groundwater from entering the tunnel.

The machines will have a slurry-handling capacity of 2,900 cubic metres per hour. The excavated material will be transported through a pumping system to a treatment plant.

The BMC is currently undertaking piling work and constructing the launching shaft at Charkop, from where tunnelling operations will begin.

“After the consignments arrive, the machinery will be assembled at the Charkop site. We are aiming to commence tunnelling with the first TBM by May 2027,” a senior BMC official said.

The 22.93-km Coastal Road North project is estimated to cost Rs 16,621 crore and will include elevated roads, bridges and underground tunnels.

The 3.9-km Mindspace-Charkop section is divided into two tunnels. The northbound tunnel is estimated to cost Rs 2,911 crore, while the southbound tunnel is estimated at Rs 2,910 crore.

Once completed, the larger corridor is expected to provide an alternative north-south road connection between Mumbai’s western suburbs and reduce dependence on existing arterial roads.