Kolkata's ambitious Purple Line Metro project has achieved a significant engineering feat, successfully guiding a massive tunnel-boring machine beneath the historic grounds of the Royal Calcutta Turf Club (RCTC). This delicate operation marks a pivotal moment in the construction of the Joka-Esplanade corridor.
A Delicate Passage Under Heritage
The first of the twin tunnel-boring machines (TBMs), named TBM Durga, completed its careful journey underneath the RCTC's heritage stands by the end of November. The stands, founded in 1901 and 1902, are considered the soul of the iconic racecourse, which was established in 1847. Engineers from the Rail Vikas Nigam Limited (RVNL) worked in close coordination with the club's own technical team to ensure a safe passage.
"It was a tricky affair waiting and watching for the first of the twin giant TBMs pass below RCTC, which is our soul," remarked Danny David, a long-time associate of the club. To safeguard the historic structure, RVNL fitted the stands with live monitoring sensors to detect even the slightest ground settlement during the tunnelling process.
Journey of the Giant Borer
TBM Durga, which began its excavation for the Esplanade-bound tunnel on July 10 last year, covered approximately 600 meters to reach the racecourse zone. The colossal machine is about 100 meters long, weighs 600 tonnes, and boasts an outer diameter of 6.6 meters. Having cleared the RCTC, it now enjoys a straight path towards the upcoming Victoria Memorial station.
Once Durga reaches the Victoria station site, it will be extracted and then relaunched to dig a further 900-meter stretch towards Park Street. Its sibling, TBM Divya, which is boring the parallel tunnel, has reached Tolly's Nullah and is expected to arrive under the RCTC next month.
Project Timeline and Scale
RVNL, the agency implementing the 14-kilometer Joka-Esplanade Purple Line, has outlined a clear timeline. The first phase of tunnelling from Kidderpore to Victoria is slated for completion by December 2026. Durga is projected to arrive at Victoria by June this year, with Divya following in December. Overall tunnelling up to Park Street should conclude by March 2027.
The two TBMs were initially lowered into a massive launching shaft at St. Thomas' Boys' School in Kidderpore. This shaft measures 37 meters long, 22 meters wide, and 17 meters deep. Their current work is part of the drive to complete the 1.7-kilometer underground section between Kidderpore and Park Street. Currently, the Purple Line operates on an 8-kilometer elevated stretch between Joka and Majerhat.
A Link to Royal History
The RCTC holds a special place in Kolkata's social history and has witnessed royal visits. Notably, Queen Elizabeth II and Prince Philip, the Duke of Edinburgh, visited the club in February 1961. During her visit on February 18, the Queen presented her own trophy at the Queen Elizabeth II Cup tournament. The prestigious Queen's Cup, originally called the Victoria Cup, has been contested at the RCTC since 1856. Interestingly, the Queen also visited the Victoria Memorial Hall, which is another site for a future Purple Line station, further linking the metro's route to the city's heritage tapestry.
