Mumbai, Feb. 4 -- The National High Speed Rail Corporation Limited (NHSRCL) is still awaiting three tunnel boring machines (TBM) from China which will be used to construct the 21-kilometre tunnel between Shilphata and Bandra Kurla Complex (BKC) on the Mumbai-Ahmedabad bullet train corridor. "Of the three TBMs required for tunneling works, we have received over 60% of the parts for the first TBM. The remaining portions of this TBM are expected to arrive in the coming days. Two other TBMs are still stuck in ports in China," an official from NHSRCL told HT, requesting anonymity. The three TBMs were manufactured and assembled at Herrenknecht AG's China unit nearly two years ago, in mid-2024. There is no clarity on when the other two might arrive, officials said. The 21-km tunnel includes a 7-km undersea tunnel across the Thane Creek. Around 5 km of the tunnel, between Shilphata and Ghansoli, has been dug using the New Austrian Tunnelling Method (NATM), while the remaining 16 km will be constructed using TBMs. The NHSRCL is, meanwhile, making steady progress on tunneling through mountains on the bullet train route. On Tuesday, breakthrough was achieved on the second mountain tunnel out of seven planned along the route. The 454-metre-long tunnel located at Dahanu was excavated from both ends using the NATM. "This was the second breakthrough of a mountain tunnel in less than a month. The breakthrough of the previous one at Saphale was achieved on January 2," a second NHSRCL official said. "We aim to achieve breakthroughs in the remaining five mountain tunnels by August. In Gujarat, all civil works for the project are expected to be completed within this year," the official noted. As of January 27, around 334 km of viaducts, 17 river bridges, and 12 major crossings over national highways, railways, and other infrastructure have been completed. Track laying and electrification works have picked up pace in Gujarat, while in Maharashtra, the project's longest river bridge over Vaitarna has reached pier level....