Work on India’s first high‑speed rail corridor continues to advance across multiple sections, but the most technically challenging component—the 21‑km underground tunnel in Mumbai, including a 7‑km undersea stretch beneath Thane Creek—remains on hold pending the arrival of three tunnel boring machines (TBMs) from China.

The National High Speed Rail Corporation Limited (NHSRCL) has confirmed that more than 60 per cent of the components for the first TBM have already reached India, with the remaining parts expected soon. The other two TBMs, however, remain stuck at Chinese ports with no confirmed delivery timeline. All three machines were manufactured at Herrenknecht AG’s China facility in mid‑2024.

These TBMs are essential for completing the remaining 16 km of tunnelling between Shilphata and Bandra Kurla Complex (BKC). Approximately 5 km of tunnelling between Shilphata and Ghansoli has already been completed using the New Austrian Tunnelling Method (NATM), but the undersea section and the final approach to BKC require TBM deployment.

While the Mumbai section awaits full‑scale TBM operations, progress continues elsewhere along the corridor. On 3 February 2026, a breakthrough was achieved in the second mountain tunnel (MT‑6) in Palghar district. The 454‑metre tunnel, excavated from both ends using NATM, was completed within 12 months. This follows the earlier breakthrough of MT‑5 at Saphale on 2 January.

The arrival of the remaining TBMs will determine the pace at which the critical undersea tunnel advances, making their release from China a key dependency for the Mumbai underground works.

Project Fact Box

Project: Mumbai–Ahmedabad High‑Speed Rail (MAHSR)

Implementing Agency: National High Speed Rail Corporation Limited (NHSRCL)

Total Corridor Length: 508 km

Underground Section: 21 km (Shilphata–BKC)

Undersea Tunnel: 7 km beneath Thane Creek

Tunnelling Methods: NATM (completed sections), TBM (pending undersea and BKC approach)

TBMs Required: 3 Herrenknecht mixshield TBMs (manufactured in China, mid‑2024)

TBM Status:

First TBM: Over 60% of parts delivered to India

Remaining two TBMs: Delayed at Chinese ports

Progress to Date:

• ~5 km NATM tunnelling completed between Shilphata and Ghansoli
• MT‑6 breakthrough (454 m) on 3 February 2026
• MT‑5 breakthrough on 2 January 2026

Key Challenges have been the delayed TBM shipments affecting the start of undersea tunnelling. 07/26.