Fadnavis Launches ₹8,056-Crore Orange Gate–Marine Lines Tunnel, India’s Most Complex Urban Underground Project

Maharashtra Chief Minister Devendra Fadnavis on Wednesday officially launched the Tunnel Boring Machine (TBM) work on the Orange Gate to Marine Lines section

The project, estimated at Rs 8,056 crore, will cut travel time by 15 to 20 minutes linking Eastern Free Way to Marine Drive by 2028.

The total corridor length spans approximately 9.239 kilometers, featuring a crucial twin-tube underground tunnel section covering about 6.51 kilometers. Fadnavis described the project as an 'engineering marvel,' as it represents India's first urban tunnel of this complexity, passing beneath some of South Mumbai’s most densely populated areas and critical existing infrastructure.

The tunnel's path is a testament to sophisticated urban planning and engineering. It will dive to depths of up to 52 meters, successfully navigating beneath major transport lines. Crucially, the alignment passes below both the Central and Western Railway tracks and, most challenging, runs approximately 50 meters below the existing underground Mumbai Metro Line 3 (Aqua Line). Furthermore, the planning minimises surface disruption by passing beneath over 700 structures, including numerous heritage properties in areas like Dongri and Khetwadi, showcasing a meticulous design approach.

Each tube features two main traffic lanes, each 3.2 meters wide, along with a dedicated 2.5-meter emergency lane. The designed speed limit inside the tunnel is capped at 80 km/h. To ensure maximum safety, cross passages connecting the two tunnels will be constructed every 300 meters, allowing for quick evacuation or emergency response. The facility will also be equipped with fire-resistant systems, modern lighting, mechanised ventilation, and an Intelligent Transport System (ITS) for seamless traffic management.

This new link will provide a crucial high-speed connection between the city's eastern and western suburbs.

Importantly, the corridor integrates with Mumbai’s other mega-projects, linking the Eastern Freeway and MTHL directly to the Coastal Road at Marine Drive. This integration will create an ultra-fast mobility loop that connects the Navi Mumbai International Airport (via the Atal Setu/MTHL) through the Eastern Freeway and across to the Western suburbs via the Coastal Road and the Bandra-Worli Sea Link, marking a major step toward a truly integrated metropolitan transport network.

This project, part of 'Paatal Lok', has been taken up by Mumbai Metropolitan Region Development Authority (MMRDA) and the contract for executing the project has been awarded to Larsen and Toubro (L&T).

Meanwhile the lowering of the TBM near Orange Gate at the southern end of the Eastern Express Highway has created panic among residents of the UNESCO-listed stretch, who fear their decades-old structures could face damage once tunnelling reaches the reclaimed land.