Bullet Train achieves milestone: Additionally Driven Intermediate Tunnel (ADIT) completed at Ghansoli

The Mumbai-Ahmedabad Bullet Train Project has reached a significant milestone with the successful excavation of the 394-metre-long Additionally Driven Intermediate Tunnel (ADIT) at Ghansoli. This achievement will facilitate two-face tunnelling for the 21 km long main tunnel, part of the NATM segment, between Bandra Kurla Complex (BKC) and Shilphata.

More Details:

The Additional Driven Intermediate Tunnel (ADIT) of 394 metres at Ghansoli for Mumbai-Ahmedabad Bullet Train Project under National High-Speed Rail Corporation Limited (NHSRCL) has been excavated. This will expedite the construction of a 21 km long tunnel between BKC and Shilphata in Maharashtra.

Brief about ADIT:

  • The 26-metre-deep inclined ADIT will facilitate construction of the 3.3 km (approx.) tunnel through New Austrian Tunnelling Method (NATM), by allowing simultaneous access for tunnelling 1.6 metre (approx.) on each side. Out of 21 km of tunnelling works, 16 km is through Tunnel Boring Machines and the remaining 5 km is through NATM.
  • The excavation work for ADIT was started on 6th December 2023, and the entire length of 394 metres was excavated in a short duration of six months. Total 214 controlled blasts were done using 27,515 kg explosives under supervision of experts and a high level of instrumentation was used to ensure safe excavation.
  • The ADIT of internal dimension: 11 metre X 6.4 metre will give direct vehicular access to the main tunnel during construction and operations and may also be used for the purpose of evacuation process in emergency situations.

A number of monitoring instruments are being used to ensure safe excavation of the tunnel and all the structures in the nearby area. Some of the instruments being used for the work are SSP (Surface settlement Points), ODS (Optical displacement Sensor) or tilt metre for displacement in both axis, BRT (By reflect target/3D targets), Strain Gauge for micro strains in tunnel surface, Seismograph for Peak Particle Velocity (PPV) or vibration & seismic wave monitor.

Under Construction Work:

  • The construction activities related to the (approx.) 21 km long tunnel from Mumbai Bullet Train station to Shilphata in the state of Maharashtra is progressing at a fast pace.
  • The 7 km (approx.) stretch of this tunnel will be under the sea at Thane Creek (Intertidal zone). This is the first of its kind tunnel to come up in the country.
  • The 21 km long tunnel will be a single tube tunnel to accommodate two tracks meant for up and down tracks.
  • To construct this tunnel, Tunnel Boring Machines (TBMs) with cutter heads of 13.6 metre diameter will be used.
  • Usually 6-8 Metre Diameter cutter heads are used for urban tunnels used in MRTS – Metro system, as these tunnels accommodate one track only.
  • The under construction three shafts at BKC, Vikhroli, and Sawli will facilitate the construction of a 16 km long tunnel through TBMs.


The successful completion of the ADIT tunnel at Ghansoli represents a major step forward for the Mumbai-Ahmedabad Bullet Train Project. This milestone not only facilitates the efficient progress of the main tunnel construction but also underscores the project’s commitment to cutting-edge engineering and timely execution.

Source: NHSRCL – Press Release | Images Credit: NHSRCL

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