Mumbai’s underground transformation has officially shifted into high gear. The Mumbai Metropolitan Region Development Authority has launched full-scale tunnelling on what is set to become the city’s deepest and most complex urban road tunnel, creating a direct link between Orange Gate on the Eastern Freeway and Marine Drive.
The Tunnel Boring Machine, or TBM, was flagged off at a ceremonial event by Maharashtra Chief Minister Devendra Fadnavis in the presence of Deputy Chief Minister and MMRDA Chairman Eknath Shinde, along with senior ministers and officials. With this, excavation work has formally begun on a project that is expected to fundamentally reshape east–west connectivity in South Mumbai.
A 10-km corridor beneath one of India’s densest urban zones
The road tunnel will stretch 9.96 km in total, of which nearly 7 km will be underground. In scale, depth, and technical complexity, it is unlike any road tunnel attempted so far in India’s urban core.
The TBM being deployed is a state-of-the-art Slurry Shield machine, similar to the technology used successfully on the Mumbai Coastal Road Project. Refurbished and re-manufactured locally under OEM supervision, the machine has a cutterhead diameter of 12.19 metres, a length of 82 metres, and weighs around 2,400 tonnes. Built to operate in mixed and water-bearing ground conditions, it is designed to tackle one of the most challenging geological profiles in the country.
Tunnelling under heritage, railways and metro corridors
What sets this project apart is not just its length but its alignment. The tunnel will be excavated at depths ranging from 12 metres to over 50 metres below ground. Its path cuts beneath high-rise residential and commercial towers in South Mumbai, passes under protected heritage structures, and crosses below both the Central and Western Railway corridors. It will also pass under Mumbai Metro Line 3 at a depth exceeding 50 metres.
Engineers say designing and executing works under such dense, sensitive, and live infrastructure zones demands extreme precision. The tunnel is being built to withstand high water pressure, soft marine clay, and variable rock strata commonly found along Mumbai’s coast.
Safety systems and operational design
Each tube of the tunnel will have two traffic lanes and one emergency lane, with a designed speed limit of 80 kmph. Cross passages will be provided every 300 metres for emergency evacuation. According to MMRDA, the tunnel will be fitted with advanced ventilation systems, high-grade fire protection, modern lighting, and a full Intelligent Transport System for real-time traffic and safety management.
The authority believes these systems will set a new benchmark for urban tunnel safety standards in India.
Project cost, timeline and commuting impact
The project carries an estimated cost of Rs 8,056 crore and has a planned completion timeline of 54 months. Around 14 percent of the physical work has already been completed through preparatory activity.
Once operational, the tunnel is expected to reduce travel time between the eastern and western seaboards of South Mumbai by 15 to 20 minutes. MMRDA estimates that this will also lower fuel consumption, cut down vehicular emissions, reduce noise pollution, and crucially, ease traffic pressure on already congested surface roads.
The tunnel will integrate directly with the Coastal Road and the Mumbai Trans Harbour Link, creating what officials describe as a future-ready mobility spine connecting key transport corridors across the city.
Leaders call it a transformative milestone
Calling the launch a “transformative leap” for Mumbai, Chief Minister Devendra Fadnavis said the tunnel would radically improve cross-city movement. “This tunnel will save thousands of commuter hours every day and redefine East–West connectivity. Maharashtra continues to lead in pioneering infrastructure,” he said.
Deputy Chief Minister Eknath Shinde described the start of excavation as a proud moment. “Navigating dense urban zones and heritage areas with advanced tunnelling technology is an achievement in itself. The project will ease congestion and significantly improve citizen mobility,” he noted.
MMRDA Commissioner Sanjay Mukherjee termed the project a landmark in Mumbai’s engineering journey. “This project demonstrates our capability to execute one of India’s most complex underground works with global best practices. It represents the beginning of a new tunnel-based mobility era for Mumbai,” he said.
A shift in how Mumbai expands
Beyond the immediate commuting gains, the Orange Gate–Marine Drive tunnel signals a deeper shift in how Mumbai is approaching urban expansion. With surface space increasingly constrained, the city is turning underground to unlock new mobility capacity without further straining already crowded neighbourhoods.
If completed on schedule, the tunnel will not only slice travel time across South Mumbai but also stand as one of the most technically sophisticated urban infrastructure projects in the country. For a city that has long battled with spatial limits, this deep-dig infrastructure push could define how Mumbai moves, grows, and breathes over the next decade.
