The Delhi Metro Rail Corporation announced a new update on the Delhi Metro Phase IV construction today. In its update,the DMRC said it has successfully completed the first twin tunnels breakthrough under the project.
Marking the completion of the 3-kilometre-long twin tunnels linking Derawal Nagar to Pulbangash on the Janakpuri West – R K Ashram corridor, the twin tunnel boring machines (TBMs) emerged concurrently at Pulbangash Metro Station.
As per the DMRC, this is a rare achievement where two tunnel boring machines (TBMs) have simultaneously emerged after excavating parallel tunnels. It marks a significant tunneling accomplishment, as engineers must carefully monitor the precise movement of both machines in tandem.
“Both TBMs were successfully retrieved at Pulbangash Metro Station today, in just over 14 months, covering a length of approx. 2997 metres, at an average rate of 8.2 metres per tunnel per day. This is also the longest tunnelling drive (almost3 km) in DMRC’s Phase IV works,” the DMRC said.
DMRC Phase IV: Twin Tunnels breakthrough
The twin tunnels have been built at a depth of about 14-15 metres underground. They pass through densely populated areas such as Rana Pratap Bagh and Punjabi Basti Colony. They also pass beneath the Najafgarh drain, a particularly sensitive area due to the drain’s uncertain structural condition. Despite operating in submerged water conditions, no damage was caused to any existing structures. Additionally, the machines had to tunnel through the under-construction Ghanta Ghar station, as retrieval at that location was not feasible.
The tunnels have an internal finished diameter of 5.8 meters, with six cross passages being built to connect the two tunnels, ensuring passenger safety.