Delhi Metro Rail Corporation Ltd has 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, a release from DMRC observed.
The Tunnel Boring Machine (TBM) emerged at Lal Qila metro station site after making a 1,351m long tunnel from Kashmere Gate. This TBM was lowered at Kashmere Gate shaft on December 6, 2014 and after assembly of the TBM below the ground the initial drive began on December 26, 2014. The maximum depth of the tunnel is 16m below the earth’s surface.
The tunnel passed beneath the existing Kashmere Gate elevated metro station with the distance of between the tunnel wall and pile of the existing metro station is 1.2m. The tunnel also passed under the historical Dara Shikoh Library, Lothian Bridge (Delhi – Shahdara Northern Railway Line), Magazine Gate and Ambedkar University, the release added.
Earth Pressure Balancing Type TBM was used to concrete the tunnel. The TBM was supplied by Terratec, an Australia headquartered company that has presence in India. A total of 967 rings were inserted simultaneously along with the tunneling process. Each ring has five segments (each 275 mm thick) and the length of one segment is 1.4m. These segments and rings are connected by using bolts. The internal diameter of the tunnel is 5.8m. The casting of the segments was done at the Mundka casting yard.
The contractor for the tunneling work was a joint venture between Metrostroy and Era Infra Engineering. 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 a 1,356m long tunnel on the “down” line. 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 km long is already operational for the general public.