In a significant milestone for India’s first bullet train corridor, a 5 km long tunnel has been completed between Ghansoli and Shilphata, marking a major achievement in the construction of the Mumbai-Ahmedabad high-speed rail corridor. This tunnel, part of the 21 km undersea stretch of the project, paves the way for the final stages of tunnelling and future installation of key infrastructure.
Breakthrough in tunnelling with NATM technology
The newly completed tunnel, measuring 4.881 km in length, is constructed using the New Austrian Tunnelling Method (NATM), a specialised technique employed to tackle complex geological conditions. The tunnel, with an internal width of 12.6 meters, will connect the Mumbai–Ahmedabad bullet train’s viaduct at Shilphata.
Tunnelling work for this section commenced in May 2024 and progressed through three faces. The first breakthrough for the 2.7 km continuous stretch was achieved on 9th July 2025, marking a significant milestone in the project’s construction. The completion of this stretch means the tunnelling work is now 4.881 km finished, and the tunnel will eventually link to the wider infrastructure at Shilphata.
Engineering success and safety measures
The tunnel construction has been carried out under challenging conditions, requiring precise engineering work including drilling, blasting, and survey operations. To enhance the tunnelling process, an Additional Driven Intermediate Tunnel (ADIT) was built, allowing excavation from both Ghansoli and Shilphata simultaneously.
The safety of workers has been prioritised with comprehensive measures, such as ground settlement markers, piezometers, and strain gauges, to monitor the tunnelling activities. Fresh air is pumped into the tunnel to maintain a safe working environment, and access to the construction site is restricted to authorised personnel only.
Tunnel design and future work
The completed tunnel will be a single-tube structure with a 13.1-meter diameter to accommodate twin tracks for both up and down lines. The remaining 16 km of the tunnel will be completed using Tunnel Boring Machines (TBMs), an efficient and safe method to handle the rest of the construction.
Overall project progress
The Mumbai-Ahmedabad Bullet Train project is progressing at a rapid pace, with various key milestones already achieved. Here are some highlights of the ongoing work:
- Viaduct and pier construction: 321 km of viaduct and 398 km of pier work have already been completed.
- Bridges: Construction of 17 river bridges and 9 steel bridges has been successfully finished.
- Noise barriers: Over 400,000 noise barriers have been installed along a 206 km stretch.
- Track bed and OHE masts: 206 km of track bed construction is complete, and more than 2,000 Overhead Equipment (OHE) masts have been installed, covering approximately 48 km of the mainline viaduct.
- Mountain tunnels: Excavation work on seven mountain tunnels in Palghar district is currently underway.
- Station work: Superstructure work on all stations in Gujarat is progressing, with advanced work on all three elevated stations. Base slab casting is also in progress for the Mumbai underground station in Maharashtra.
A step towards a high-speed future
The completion of the 5 km tunnel is a crucial step in realising the vision for India’s first bullet train corridor. With rapid progress on various fronts, the Mumbai–Ahmedabad high-speed rail project is set to revolutionise travel between these two major cities, offering speed, efficiency, and cutting-edge technology for Indian commuters.