The breakthroughs on June 9 and 29 mean the company has completed eight tunnel drives for the project.
Larsen & Toubro says the most critical phase of this stretch was the crossing beneath the Rajendra Nagar Terminal, a vital artery of the Delhi–Howrah mainline that handles nearly 108 train movements daily. The team worked in co-ordination with the East Central Railway, Delhi Metro Rail Corporation, and Patna Metro Rail Corporation to implement a temporary speed restriction over a 24-day window.
During this timeframe, the TBMs executed an 80m crossing beneath five railway lines and four platforms. Throughout this delicate operation, the team maintained tunnel-induced ground settlement at under 4mm – significantly below the permissible design threshold of 10mm.
Larsen & Toubro says the tunnel excavation required navigating an array of challenges, from advancing through complex mixed soil sub-nominal groundwater levels to tunnelling beneath heritage structures and dense neighbourhoods while managing intricate utility networks.
Patna Metro Package PC-03 is an 8km underground section of Corridor 2 (Patna Junction to New ISBT). It includes the excavation of twin tunnels – 6km built by shield TBM and a cut-and-cover sction; an underground ramp at Rajendra Nagar; and the construction of six stations: Rajendra Nagar, Moin Ul Haq Stadium, Patna University, PMCH, Gandhi Maidan, and Akashvani.
