New Delhi: The Delhi Metro Rail Corporation (DMRC) on August 4, achieved a tunnel breakthrough of Delhi Metro’s Phase – III project at the Lal Qila Metro station by completing the tunneling on the under construction Kashmere Gate – Lal Qila stretch of the Central Secretariat – Kashmere Gate Corridor.
The Tunnel Boring Machine (TBM) emerged at Lal Qila metro station site after making a 1351 metre-long tunnel from Kashmere Gate. This TBM was lowered at Kashmere Gate shaft on 6th December 2014 and after assembly of the TBM below the ground the initial drive began on 26th December 2014. The maximum depth of the tunnel is 16 mts below the earth’s surface.
The tunnel passed beneath the existing Kashmere Gate elevated Metro Station. The distance of between the tunnel wall and Pile of the existing metro station is 1.2 metres. The tunnel also passed under the historical Dara Shikoh Library, Lothian Bridge (Delhi – Shahdara Northern Railway Line), Magazine Gate and Ambedkar University.
Earth Pressure Balancing Type TBM was used to concrete the tunnel. A total of 967 rings have been inserted simultaneously along with the tunneling process. Each ring has five segments (each 275 mm thick) and the length of one segment is 1.4 mts. These segments and rings are connected by using bolts. The internal diameter of the tunnel is 5.8 mts. The casting of the segments was done at the Mundka Casting Yard. Approx. 46, 000 cu. mts. excavation was done in working days. The TBM used to make the tunnel is from Terratech.
M/s Metrostroy Era JV is the contractor for the tunneling work of the stretch from Kashmere Gate to Lal Qila metro station. The stations at Kashmere Gate and Lal Qila are also being constructed by the same contractor using Cut & Cover technique. Another TBM is working on the Down Line. The Down Line tunnel is 1356 mts long.
This section is a part of the 9.37 km long Central Secretariat – Kashmere Gate corridor. The section from Central Secretariat to ITO which is 4.2 kms long is already operational for the general public.