Delhi Metro Achieves Major Milestone In Phase 4 Expansion With Tunnel Breakthrough

The Delhi Metro Rail Corporation (DMRC) has reached a significant milestone in its Phase 4 expansion on the Golden Line, successfully completing an underground tunnel between Chhatarpur Mandir and IGNOU Station on the Tughlakabad-Aerocity corridor, PTI reported.

In an official statement, the DMRC announced, "Tunnel Boring Machine (TBM) broke through at IGNOU Station after completing a 1,475-metre-long tunnel. The breakthrough was achieved using a 97-metre-long TBM, with two parallel circular tunnels being constructed for up and down movement."

This tunnel is built at an average depth of 26 metres, going up to 36 metres at the deepest point and 15 metres at the shallowest, making it one of Delhi Metro's deepest structures underground.

The tunnel has 1,048 rings with an inner diameter of 5.8 metres.

Anuj Dayal, principal executive director, corporate communications at DMRC, highlighted the significance of the achievement, stating, "This breakthrough marks another important step in our Phase 4 expansion, overcoming significant geological challenges to ensure seamless progress."

Earth Pressure Balancing Method (EPBM) was utilised in constructing the tunnel, with precast concrete tunnel rings made at a mechanized casting complex in Mundka.

The precast concrete rings were steam-cured to further increase their strength at a high rate.

Tunnelling drive, which had started on 4 December 2023, was quite a challenging one under a steep incline and the mixed geology of mica and hard rocks.

The challenging landscape even resulted in the damage to the screw auger, which had to be replaced during the construction process.

The part of the overall Phase 4 expansion, DMRC is constructing 40.109 kilometres of metro lines underground, of which 19.343 kilometres fall under the Tughlakabad-Aerocity corridor.

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