The Delhi Metro Rail Corporation (DMRC) on Wednesday (December 4) completed the longest underground tunnel on the Tughlakabad-Aerocity corridor of Phase-IV, between the Tughlakabad Airforce Launching Shaft and Maa Anandmayee Marg.
A 105-meter-long tunnel boring machine (TBM) successfully broke through at the Maa Anandmayee Marg station this morning, after boring a 2.65-km stretch. The work on this section involves constructing two parallel circular tunnels for up and down movement. The breakthrough for the other parallel tunnel is expected by January 2025.
40.1 km of underground metro lines under construction
As part of the ongoing Phase-IV project, a total of 40.109 kilometers of underground lines are being built, with the Aerocity-Tughlakabad corridor comprising 19.343 kilometers of underground sections.
The new tunnel, built at an average depth of 16 meters, has a diameter of 5.8 meters and is lined with about 1,894 precast concrete rings. The tunneling work, which used Earth Pressure Balancing Method (EPBM) technology, faced significant technical challenges, including the relocation of a sewer line and drilling through hard rock strata.
The tunnel rings were cast at a fully mechanised yard in Mundka and cured using a steam curing system to enhance early strength. During construction, all necessary safety measures were taken, including monitoring ground movement with sensitive instruments to prevent any settlement near existing structures.