"DMRC Completes Tunnel Under Red Line at Pulbangash Without Disrupting Train Services"

The Delhi Metro Rail Corporation (DMRC) has successfully completed a technically challenging tunnelling operation under the operational Red Line at Pulbangash as part of its Phase-IV expansion, officials said recently. The tunnel forms a key part of the Janakpuri West–RK Ashram Marg extension of the Magenta Line, connecting the Pulbangash and Sadar Bazar stretch.

Trains on the busy Red Line, which carries nearly seven lakh passengers daily, continued to run uninterrupted throughout the operation, even as the tunnel boring machine (TBM) worked just below the elevated viaduct. The structure at the site sits on open foundations with a balanced cantilever span, making tunnelling beneath it especially sensitive.

To ensure safety, engineers implemented a detailed ground-strengthening plan around the existing pier, including the use of the Tube-a-Manchette (TAM) grouting technique. This involved creating 180 boreholes around the pier, which were filled with high-strength cement grout to stabilise the soil, fill voids, and prevent settlement during tunnelling.

DMRC also deployed extensive monitoring instruments to track ground movement, pier behaviour, and the condition of nearby buildings in real time. The downline tunnel has now been completed, while work on the up-line tunnel continues under similar precautions.

Officials emphasized that the successful completion of this operation without service disruption demonstrates DMRC’s technical expertise and commitment to minimizing inconvenience to commuters.