DMRC achieves twin tunnel break through as part of phase 4 expansion

The Delhi Metro Rail Corporation (DMRC), as part of its phase 4 expansion, on Wednesday completed a twin tunnel break through — two tunnel boring machines (TBMs) burrowing through parallel passages — on a 3km shaft between the upcoming Derawal Nagar and Pulbangash stations on the Magenta Line, officials said.
“This is one of those rare occasions when two TBMs have emerged simultaneously after boring parallel tunnels. It is a major tunnelling feat as the engineers have to meticulously monitor the movement of two parallel machines. Both TBMs were retrieved at Pulbangash Metro station, in just over 14 months, covering a length of approximately 2997 metres, at an average rate of 8.2 metres per tunnel per day. This is also the longest tunnelling drive in DMRC’s phase 4 works,” said DMRC spokesperson Anuj Dayal.
Officials said the tunnels were built at a depth of 14-15m, passing through densely populated areas such as Rana Pratap Bagh and Punjabi Basti colony. The TBMs — named Bhoomi and Srishti — also passed beneath the Najafgarh drain, a sensitive section due to the uncertain structural condition of the drain.
“Despite tunnelling in submerged water conditions, no damage was caused to any existing structures. The TBMs also had to bore through the under-construction Ghanta Ghar station as retrieving them at that location was not feasible. The tunnels have an internal finish diameter of 5.8 metres, and a total of six cross passages are being constructed to connect the two tunnels for passenger safety,” said Dayal.
This is not the first time DMRC has completed a twin tunnel break through — earlier, during the phase 3 expansion of the Metro network, two TBMs made a break through at the Dabri station on the Magenta Line, an official said.
DMRC, as part of its phase 4 expansion, is constructing 65.2km of rail tracks across three priority corridors — Janakpuri West to RK Ashram Marg (28.92km, which will be an extension of the existing Magenta Line), Majlis Park to Maujpur (12.55km, which will be an extension of the Pink Line), and the new 23.62km Golden Line.