Mumbai: The Western Railway (WR) has received a go-ahead from the Railway Board to conduct a feasibility study for a tunnel linking Churchgate and Mumbai Central, since there are multiple constraints in laying additional tracks alongside the four existing railway lines on this stretch, officials familiar with the matter told Hindustan Times.Picture for representation (HT Photo)The proposed tunnel will be used to accommodate suburban locals and segregate lines for long-distance trains, and it may be extended till Prabhadevi depending on the need and feasibility, officials said.“We will soon begin a final local survey (FLS) for the proposed rail tunnel. We will examine the requirement for this tunnel and on that basis decide the route should follow,” a senior WR official said, requesting anonymity.To be sure, the cost of constructing underground rail tunnels in Mumbai, at ₹1,100 crore per km, is nearly four times the cost of contracting elevated corridors, at ₹250-300 crore per km. WR officials said the push for going underground was driven by multiple constraints on the existing network.“Adding more surface lines has become very difficult due to high land acquisition costs, dense urban development and litigation that often delays execution,” said the official quoted earlier. “A tunnel can bypass these hurdles while creating parallel capacity and enabling the segregation of suburban services from goods and long-distance trains.”The WR is already working on adding the fifth and sixth lines between Mumbai Central and Mahim, with March 2029 as the deadline. While laying the fifth line is almost complete, there has been little progress on the sixth line, officials said.“Land acquisition remains the biggest challenge for the fifth and sixth rail lines, so the deadline is still three years ahead. During the survey for the proposed tunnel, we will explore if it can be an alternative to the sixth line (on the Mumbai Central-Mahim stretch),” the official said.The Central Railway is also exploring a similar rail tunnel on the Parel-Chhatrapati Shivaji Maharaj Terminus (CSMT) stretch due to problems regarding land acquisition, officials said.Mum-Delhi in 12 hours from 2027Meanwhile, work on upgrading rail infrastructure in the Mumbai division for running long distance trains at 160 kmph is 90%. The upgrade is part of the Mumbai-Ahmedabad-Delhi trunk route speed upgradation to 160 kmph.“On the signalling front, Kavach installation has been completed on the Vadodara-Ahmedabad section, while work on the Nagda-Mumbai Central stretch is 80-95% complete on various stretches. The ongoing work is on the suburban network,” said a senior railway official.All major civil engineering work on the Nagda-Mumbai Central and Vadodara-Ahmedabad sections is complete, and pending work include installation of crossings and rehabilitation of bridges on the Virar–Surat section, likely to be completed by December 2026.Once the infrastructure upgrade is complete, trials will be conducted for train operations at 160 kmph. If all goes as planned, trains will be able to cover the Mumbai–Delhi route in just 12 hours 2027 onwards.