Delhi Metro's Underground Engineering Triumph
In a remarkable display of engineering precision, the Delhi Metro Rail Corporation (DMRC) has successfully constructed an underground tunnel at Pulbangash directly beneath the operational Red Line of the Delhi Metro network. This significant achievement was accomplished without halting train services on the busy Red Line for even a single day, marking a major milestone in urban infrastructure development.
The Challenging Tunneling Operation
The tunneling work formed part of the upcoming Janakpuri West–RK Ashram Marg corridor, which represents an extension of the Magenta Line. The specific tunnel section was built between Pulbangash and Sadar Bazar stations, presenting extraordinary challenges due to its position below active metro lines.
According to Anuj Dayal, Principal Executive Director of Corporate Communications at DMRC, the operation required exceptional engineering precautions. "This tunnelling work was particularly challenging as the Tunnel Boring Machine (TBM) had to carefully construct the tunnel below the elevated viaduct while trains remained operational above," Dayal explained. "The Red Line viaduct stands on open foundations with a balanced cantilever span, making the tunneling beneath such a structure exceptionally complex."
Advanced Engineering Solutions Implemented
DMRC implemented several sophisticated measures to ensure the success of this tunneling feat. A comprehensive strategy was developed to strengthen the area around the Red Line's pier foundation. The corporation employed an advanced grouting program called TAM (Tube-a-Manchette) technology, which involved installing 180 TAM boreholes around the pier structure.
Following the installation, high-strength cement grouting was performed to achieve multiple objectives: stabilizing the soil composition, filling existing voids, and significantly increasing the load-bearing capacity of the foundation area. This meticulous approach ensured that the structural integrity of the elevated Red Line remained uncompromised throughout the tunneling process.
To maintain real-time safety monitoring, DMRC deployed multiple instruments that continuously tracked ground movement, pier behavior, and building safety parameters. Specialized technical personnel were assigned to monitor these equipment readings 24/7, providing constant oversight during the critical construction phase.
Current Status and Future Implications
The construction milestone represents significant progress for Delhi's expanding metro network. The downline tunnel on this challenging section has been successfully completed, while work on the up-line tunnel continues to advance. This engineering accomplishment demonstrates DMRC's growing expertise in executing complex infrastructure projects in densely populated urban environments without disrupting existing services.
The successful completion of this tunneling operation sets a new benchmark for metro construction projects worldwide, particularly those requiring construction beneath operational transportation infrastructure. It showcases Indian engineering capability in addressing complex urban challenges while maintaining uninterrupted public services.
