Kolkata: The Purple Line of the Kolkata Metro plans to leverage the modern Tunnel Boring Machine (TBM) technique to dig the 1.6km tunnel from Esplanade to Eden Gardens instead of the traditional Cut-and-Cover method.
The Indian Railway Board had already sanctioned Rs 1000 crore for the expansion of the Purple Line of Kolkata Metro. However, the line starting from Joka will not terminate at Esplanade. Instead, it will continue for another 1.6 Km up to Gate No 1 of Eden Gardens.
The Purple Line will extend for a distance of 17 km. The portion between Joka to Mominpur will be on an elevated line. The rest from Khidirpur onwards will.be underground.
There will.be a blend of two methods used for this underground portion. The TBM method will be used to dig the tunnel between Khidirpur and Park Street.
However, the 500 m stretch between Park Street and Esplanade will be dug using the traditional cut-and-cover method. This is being done while keeping in mind the disaster in the Bowbazar area a few years ago while digging using the TBM method.
From Esplanade to Eden Gardens, the last 1.6 km stretch will again.be done using the TBM method.
The shaft to lower the boring machine has been dug at St Thomas school grounds in Khidirpur. The machine will come down this shaft and reach Park Street.
The tunnel boring machine (TBM) from Esplanade to Eden Gardens will take a different route at the former L 20 bus stand. Proceeding underground, it will travel along Rani Rashmoni Road towards Raj Bhavan, bypass the East-West Metro station, and then go beneath the Raj Bhavan premises to reach the Eden Gardens station.
