The Railway Ministry on Sunday (July 5, 2026) postponed the formal launch of tunnel-boring work for the bullet train project in Mumbai due to inclement weather and told authorities to commence the work immediately.

Ministry officials said it has been raining in Mumbai for the past few days, and the India Meteorological Department (IMD) has issued 'red' and 'orange' alerts for the next couple of days.

Mumbai-Ahmedabad bullet train: Tunnel breakthrough achieved in Palghar district; 3rd in 5 months

"Considering the adverse weather conditions, we have decided to postpone the formal launch by the Hon'ble Railway Minister of the underground tunnel boring work using tunnel boring machines for the first time on the bullet train project," a senior official said.

"However, we have asked the National High Speed Rail Corporation Limited (NHSRCL) to start the work immediately without the official launch so that the project is not delayed," the official added.

The underground tunnel-boring work, being done by Afcons Infrastructure Limited, will now start the TBM operation for the timely completion and launch of the bullet train between Mumbai and Ahmedabad, NHSRCL officials said.

Railway Minister Ashwini Vaishnaw was scheduled to inaugurate the underground tunnel-boring work from Vikhroli to the Bandra Kurla Complex station in Mumbai on Sunday (July 5, 2026), marking the maiden use of a tunnel boring machine for the country's first bullet train project, between Mumbai and Ahmedabad.

Imported via sea route from China in March 2026, the two customised German-made tunnel-boring machines (TBMs) are owned by Afcons Infrastructure Limited, which is constructing a 20.37-km tunnel, including a 7-km undersea stretch. The tunnel will be built at a depth of around 65 metres below ground level.

Officials said the first TBM will begin tunnelling from Vikhroli towards the BKC station, covering a distance of approximately 5.8 km.

The second TBM is currently being assembled at Sawli and is expected to be ready within a week. It will excavate the 9.7-km stretch from Sawli to Vikhroli, including the 7-km undersea section.

Each TBM is expected to excavate around 300 metres of tunnel every month. Once both machines become operational, around 600 metres of tunnelling will be completed every month.

Explaining the project, officials said the 20.37-km tunnel stretches from the BKC station to Shilphata.

"Of the total length, 15.4 km between BKC and Sawli will be excavated using TBMs. The remaining 4.8-km stretch from Sawli to Shilphata has already been completed using the drill-and-blast method," they said.

The tunnel will be a single-tube pathway which will accommodate twin tracks for bi-directional traffic.

Two shafts at Vikhroli and Sawli, at approximate depths of 56 and 39 metres, will facilitate the construction. Thirty-nine equipment rooms at 37 locations will also be constructed adjoining the tunnel as part of the package.

These TBMs are among the largest and most expensive heavy machinery to be deployed in India.

Each has a cutter-head diameter of 13.6 metres, making them among the biggest tunnel boring machines used in any railway project nationwide.

By comparison, TBMs used for urban metro rail systems typically have cutter-head diameters of 5 to 6 metres.

The Mumbai-Ahmedabad High-Speed Rail Corridor, India's first bullet train project, spans 508 km and aims to provide high-speed connectivity between Maharashtra and Gujarat.