Published Date: 20-09-2025

This NATM (New Austrian Tunnelling Method) tunnel of approximately 5 km (4.881 km) length is part of the 21 km undersea tunnel between BKC and Shilphata, which includes a 7 km stretch under Thane Creek.

Tunnelling for this stretch commenced through three faces in May 2024. The first breakthrough for the initial 2.7 km continuous tunnel section was achieved on 09th July 2025 (between ADIT and Savali shaft). With this breakthrough, a continuous stretch of 4.881 km of tunnel has been completed between Savali shaft and the tunnel portal at Shilphata.

The tunnel will connect to the viaduct portion of the MAHSR project at Shilphata. This NATM tunnel has an internal excavation width of approximately 12.6 meters.

The breakthrough marks the completion of excavation works in complex geological conditions and validates the successful application of engineering techniques such as drilling and blasting, survey works, and support systems. This allows the project to move into the final stages including waterproofing, lining, finishing, and equipment installation.

To accelerate the tunnelling process, an Additional Driven Intermediate Tunnel (ADIT) was constructed, enabling simultaneous excavation from both Ghansoli and Shilphata sides.

The remaining 16 km of tunnelling will be carried out using Tunnel Boring Machines (TBMs). The tunnel will be a single-tube tunnel with a diameter of 13.1 meters, designed to accommodate twin tracks for both up and down lines.

Comprehensive safety measures have been implemented at the site, including ground settlement markers, piezometers, inclinometers, and strain gauges to ensure safe and controlled tunnelling activities without disturbing nearby structures.

Proper arrangements have been made to restrict access to the tunnel construction sites, preventing unauthorized entry and ensuring the safety of workers in this sensitive and complex construction environment. Adequate provisions have also been made for supplying fresh air inside the tunnel for construction workers.

India’s first 508 km long Bullet Train corridor between Mumbai and Ahmedabad continues to make steady progress:

• 321 km of viaduct and 398 km of pier work completed

• 17 river bridges and 09 steel bridges completed

• More than 4 lakh noise barriers installed across 206 km stretch

• 206 track km of track bed construction completed

• Over 2000 OHE masts installed covering approximately 48 km of mainline viaduct

• Excavation work ongoing for 7 mountain tunnels in Palghar district

• Superstructure work on all stations in Gujarat at advanced stage

• Work underway on three elevated stations and Mumbai underground station base slab in Maharashtra