L&T’s Heavy Civil Infrastructure team touches a double highpoint
Two tunnel breakthroughs are indeed a feat! This was achieved by L&T’s Heavy Civil Infrastructure team on the Patna Metro project in June.
The two tunnel-boring machines (TBMs) tunnelled in parallel, with a 100 m lag, from Moin-Ul-Haq Stadium Station towards Rajendra Nagar Station, each excavating approximately 700 m before breaking through the diaphragm wall at Rajendra Nagar Station. This marks yet another significant achievement in the execution of the project’s underground works.
This stretch posed a formidable array of engineering and operational challenges. The alignment required tunnelling beneath active railway tracks, navigating through densely built neighbourhoods with heritage structures, and advancing through complex mixed geological strata along a steep tunnel gradient. Mixed soil below sub-nominal groundwater levels further intensified the risk, compounded by the need to break through diaphragm walls interlaced with intricate municipal utility networks at the headwall.
The team meticulously optimised TBM parameters, while maintaining continuous monitoring of both surface and subsurface instrumentation. Round-the-clock vigilance by a multidisciplinary Emergency Response Team ensured uncompromised safety and precision.
A defining achievement was the drama beneath the highly congested railway corridor at Rajendra Nagar Terminal, part of the critical Delhi-Howrah mainline, which sees nearly 108 train movements daily – including premier semi-high-speed services such as Vande Bharat, Namo Bharat, Tejas and Rajdhani Express. The feat was accomplished through close coordination and effective teamwork among officials of East Central Railway, Delhi Metro Rail Corporation (DMRC) and Patna Metro Rail Corporation (PMRC) and L&T. Special permission was secured from Indian Railways to temporarily restrict train speeds to 10 km/h over a 24-day window, enabling the TBMs to execute a flawless 80m-long crossing beneath 5 railway lines and 4 platforms, while maintaining tunnel-induced ground settlement within the exceptional limit of under 4 mm.
The breakthroughs were graced by Sandeep Kumar R Pudkalkatti (Secretary UDHD-cum-MD, PMRC) and S N Joshi (PD – DMRC). The project team was represented by Aloke Kumar Dey (Project Director), Monu Govil (Dy Project Manager) and Arvind Kumar Tyagi (DPM – Tunnel). The officials appreciated the efforts of the project team in overcoming the challenging conditions to achieve this milestone.
