Lucknow in India is celebrating the completion of the city’s first TBM-driven tunnels as part of the 22.88km Lucknow Metro North-South line.
Two 6.52m diameter Terratec earth pressure balance (EPB) machines, named ‘Gomti’ and ‘Ganga’, have simultaneously broke through at Lucknow’s Hussainganj underground metro station completing their third drives for the project, two months ahead of schedule.
Watch a video of the breakthrough here.
The event also marked the completion of tunnelling works on the 3.67km long Charbagh-Hazratganj underground stretch in a record time of approximately 15 months.
The TBMs mined through geology consisting of stiff to hard clayey silt and medium to dense silty sand, passing beneath historic buildings in the Capital Plaza of Hazratganj without any disturbance to buildings, public utilities or traffic.
The EPB machines feature a soil configuration with a spoke-style cutterhead and a 57% opening ratio. Terratec designed the cutterheads with cutting tools that are interchangeable with 430mm roller disc cutters, allowing the TBMs to bore through station D-walls and unexpected obstacles in the ground.
According to Terratec, tunnelling through the heart of Lucknow posed a number of difficulties. In particular the final drives from Charbagh to Hussainganj as the TBMs had to pass 1m below the bed of the Haider Nallah Canal in a highly populated area full of dilapidated structures on weak foundations.
Tata Projects assistant general manager Ramesh K said “During this journey, the TBMs delivered excellent performance, with no major breakdowns, crossing the Haider Nallah and so many other geological challenges along the way.
These new tunnels will now provide Lucknow – the capital of Uttar Pradesh – with its first underground metro line, bringing a modern public transportation system to a city that is currently experiencing rapid population growth and substantial traffic congestion.
Phase 2 of the scheme is due to commence later this year.