NEW DELHI: The Delhi Metro Rail Corporation (DMRC) has completed the longest underground tunnel on the Tughlakabad-Aerocity corridor of Phase-IV, marking a significant milestone in its ongoing expansion.
The tunnel stretches between the Tughlakabad Airforce Launching Shaft and Maa Anandmayee Marg, the DMRC said in a statement on Wednesday.
A 105-metre-long tunnel boring machine (TBM) broke through at Maa Anandmayee Marg station Thursday morning, after boring a 2.65-km-long tunnel, the statement added.
The DMRC is constructing two parallel circular tunnels on this stretch to facilitate up and down movement. The breakthrough for the second tunnel is anticipated in January 2025, the statement said.
The newly completed tunnel, built at an average depth of around 16 metres, required the installation of approximately 1,894 rings, each with an inner diameter of 5.8 metres. The construction posed significant technical challenges, including the relocation of a sewer line and boring through hard rock strata.
The tunnel has been built using the Earth Pressure Balancing Method (EPBM) technology and features a concrete lining made of precast tunnel rings. These rings were manufactured at a mechanised casting yard in Mundka, where steam curing was used to accelerate strength development, the statement further said.
All necessary safety precautions were taken during the construction of the tunnel below existing built-up structures. Ground movements were closely monitored with highly sensitive instruments to prevent any settlement, the DMRC noted.
The phase-IV expansion includes 40.109 kilometres of underground lines, of which 19.343 kilometres belong to the Aerocity-Tughlakabad corridor. The corridor, dubbed the Golden Line, aims to connect southern Delhi directly with the Indira Gandhi International Airport.
The Tughlakabad Metro Station is a crucial interchange facility between the Golden Line and the Violet Line. It has been designed as a four-level underground structure with a 23-metre-deep parking facility and a short subway to enhance the commuter experience and inter-line connectivity.