The Delhi Metro Rail Corporation (DMRC) is undertaking the ambitious development of over 40 kilometers of underground corridors as part of its Phase 4 expansion. This accounts for approximately 50% of the total 86 kilometers of new lines being constructed across five corridors, according to a senior DMRC official.
Expanding Underground Network
Phase 4 includes the construction of 27 underground stations, marking a significant engineering challenge as the corridors traverse densely populated residential and commercial areas such as Sadar Bazar, Nabi Karim, Mehrauli Badarpur Road, and New Delhi. A 2-kilometer underground section between Janakpuri West and Krishna Park, part of the Magenta Line extension, has already been completed.
Key corridors with significant underground stretches include:
- Aerocity-Tughlakabad: Approximately 19 kilometers
- Janakpuri West–RK Ashram Marg: Around 9 kilometers
- Inderlok–Indraprastha: Over 11 kilometers
The Majlis Park–Maujpur and Lajpat Nagar-Saket G Block corridors will not feature underground sections.
Advanced Tunnelling Techniques
The DMRC employs advanced tunnelling methods, including tunnel boring machines (TBMs) and the New Austrian Tunnelling Method (NATM), depending on the requirements. TBMs are particularly effective in congested urban areas, minimizing surface disruptions.
Currently, seven tunnelling drives have been completed across Phase 4, with nine more underway. Monitoring systems are in place to assess the structural safety of buildings above the tunnelling zones.
Challenges and Milestones
The construction involves navigating varied strata and crowded urban landscapes, making it a complex engineering endeavor. However, DMRC has a proven track record, having successfully utilized similar techniques in Phase 3, which involved 50 kilometers of underground sections.
With the Phase 4 expansion, DMRC aims to enhance connectivity and reduce congestion across Delhi, further strengthening its role as a critical mode of urban transport.