Railway Minister Ashwini Vaishnaw Inspects Undersea Tunnel Work

Railway Minister Ashwini Vaishnaw inspected the undersea tunnel work for the Mumbai-Ahmedabad High-Speed Rail Corridor on Saturday and expressed satisfaction with the “good progress” being made on this ambitious project.

The 21-kilometre tunnel, which includes a 7-kilometre stretch beneath the Thane Creek, will connect the Bandra Kurla Complex (BKC) station to Shilphata. It is India’s first undersea rail tunnel.

Speaking at the project site in Ghansoli, Vaishnaw highlighted the advanced technology and design enabling two trains to pass through the tunnel at speeds of up to 250 km/h. For single trains, the speed can reach a maximum of 320 km/h. He emphasized that the tunnel incorporates measures for environmental protection along with state-of-the-art ventilation and lighting systems.

“The construction on 340 kilometres of the project has seen significant progress,” the minister noted. However, when asked about the project’s expected completion date, he refrained from providing a specific timeline.

Vaishnaw also detailed the advancements in the project, including bridge construction over rivers and the development of station infrastructure. He added that Japanese experts have been closely inspecting and approving the ongoing work to ensure adherence to high standards.

The Union minister credited Prime Minister Narendra Modi’s vision of providing an affordable and efficient transportation mode for the middle class, stating that the high-speed rail project would integrate the economies of cities along the route, including Mumbai and Ahmedabad. “This project is not just about transportation but about economic integration. It will spur urban development, significantly reduce travel time, and enhance daily productivity,” he said.

The Mumbai-Ahmedabad High-Speed Rail corridor spans 508 kilometres with 12 stations, including Mumbai (BKC), Thane, Virar, Boisar (Maharashtra), and Vapi, Bilimora, Surat, Bharuch, Vadodara, Anand, Ahmedabad, and Sabarmati (Gujarat). The highlight of the project is the 21-kilometre undersea tunnel, which will feature a single tube accommodating twin tracks. Additionally, 39 equipment rooms are being constructed at 37 locations along the tunnel.

Vaishnaw lauded Indian engineers for their expertise and dedication to the project, calling it a matter of national pride. He also acknowledged the support and collaboration with Japanese Railway in designing the high-speed rail system.

Dedicated Casting Yard for Tunnel Linings: A specialized casting yard in Mahape, Thane district, is operational to manufacture 77,000 high-strength M70-grade concrete segments, forming 7,700 rings for the TBM section of the tunnel. The yard, spread across 11.17 hectares, houses automated casting and stacking equipment, ensuring superior quality and efficiency.

Tunneling Techniques

Of the 21 km stretch, 16 km is being excavated using advanced Tunnel Boring Machines (TBMs), while the remaining 5 km employs the New Austrian Tunneling Method (NATM).

Milestones Achieved

A 394-meter-long ADIT (Additionally Driven Intermediate Tunnel) was completed in May 2024 at Ghansoli ,enabling multiple excavation fronts. 

Total 2.2 km of NATM tunneling work has been completed including 1111 meter at Ghansoli site and  602 meters of NATM tunneling achieved at Shilphata.

At BKC, excavation for a 36-meter-deep shaft is underway.

Vikhroli has seen the completion of a 56-meter-deep shaft to deploy TBMs towards BKC and Ahmedabad .

At Savli, a 39-meter shaft excavation has been completed.

Safety and Monitoring Measures

The project employs cutting-edge safety measures, including, continuous ventilation inside tunnels to ensure a safe working environment.

Disposal of excavated material in compliance with state regulations.

Installation of geotechnical instruments such as inclinometers, vibration monitors, and ground settlement markers to monitor structural integrity around the sites.