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DMRC recently completed tunnelling work beneath the operational Red Line at Pulbangash as part of the Magenta Line extension between Janakpuri West and RK Ashram Marg. The team carried out the activity below an elevated viaduct with open foundations, which required detailed planning and ground-strengthening. Engineers used the TAM grouting method with around 180 boreholes to stabilise the pier area, supported by continuous monitoring systems. Train operations on the Red Line continued normally throughout the work. The downline tunnel is finished, and the up-line tunnel is still being constructed.
The Delhi Metro Rail Corporation has completed a key part of its phase-four construction by finishing the downline tunnel beneath the Red Line at Pulbangash. This section forms part of the Magenta Line extension connecting Janakpuri West and RK Ashram Marg, specifically the stretch between Pulbangash and Sadar Bazar. The work took place under an active elevated corridor, and despite the sensitive conditions, train operations continued normally for passengers. Advertisement
The tunnelling required passing under a viaduct that sits on open foundations supported by a balanced cantilever span. Because of this configuration, the engineering team had to design a careful ground-strengthening plan before excavation. For this purpose, they adopted the TAM (Tube-a-Manchette) grouting technique, where nearly 180 boreholes were drilled around the pier to inject high-strength cement grout. This helped stabilise the soil and ensured the viaduct remained unaffected during the tunnelling.
In addition to grouting, instruments were installed to observe ground movement and pier settlement. The monitoring also covered nearby buildings to ensure they remained stable through the construction process. Field teams supervised data and movement readings throughout the work, creating multiple layers of safety.
While the downline tunnel is now complete, tunnelling for the up-line is still progressing. The same safety plan and monitoring measures are being used to maintain structural stability and avoid any disturbance to metro services. The Red Line, which carries a high daily ridership, continued smooth operations even when work was happening directly below its structure.
DMRC has previously carried out tunnelling near sensitive structures, but this project required extra coordination due to the elevated design at Pulbangash. The milestone marks another step forward in expanding Delhi's metro network under dense urban zones where construction must be carried out without service disruption.
Source PTI
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