TBM Assembly Begins on Mumbai’s GMLR Megatunnel

Why It Matters

The GMLR tunnels will dramatically improve east‑west connectivity, easing congestion on one of India’s most densely populated corridors and showcasing advanced tunnelling technology for future megaprojects.

Key Takeaways

• India’s largest TBM deployment begins
• Two 14.42m EPB machines assembled for GMLR
• Tunnels will span 10.6km under national park
• Designed for basalt, high groundwater pressures
• Expected to cut Mumbai travel times dramatically

Pulse Analysis

Mumbai’s chronic traffic snarls have driven planners to seek underground solutions, and the Goregaon‑Mulund Link Road (GMLR) megatunnel is the city’s most ambitious. By creating a direct east‑west conduit between the Western and Eastern Expressways, the project promises to shave minutes off commutes that currently stretch across congested surface roads. The 10.6 km twin tunnels will run beneath the ecologically sensitive Sanjay Gandhi National Park, demonstrating how large‑scale infrastructure can coexist with environmental constraints when engineered thoughtfully.

The technical heart of the GMLR lies in its two 14.42 m diameter Earth Pressure Balance machines, supplied by TERRATEC and equipped with dual screw conveyors, a fourth‑row tail‑brush seal, and twin probe drilling for water ingress mitigation. These features enable the TBMs to cut through Deccan basalt and breccia at depths up to 143 m while managing high groundwater pressures—a challenge that has limited similar projects in the region. Continuous conveyor logistics and a -1.1 % gradient further streamline spoil removal, reducing cycle times and operational costs.

Beyond immediate traffic relief, the megatunnel sets a new benchmark for Indian tunnelling, signaling confidence in deploying ultra‑large diameter machines for urban corridors. The successful execution could unlock similar underground links in other megacities, fostering economic growth by improving freight movement and commuter reliability. Moreover, the project’s emphasis on advanced dewatering and ground‑treatment technologies may influence future standards, positioning India as a leader in complex, high‑pressure tunnelling environments.