Rudra, BMRCL’s tunnel boring machine, eases through last stretch

Bengaluru: Rudra, a BMRCL-operated tunnel boring machine (TBM), completed its final 718-metre tunnelling stretch from Lakkasandra to Langford Town Station in just 100 days as part of the Dairy Circle to Nagawara tunnel network.

Earlier, Rudra had completed 613.2 metres between the South Ramp and Dairy Circle station and 746.2 metres between the Dairy Circle station and Lakkasandra station.

This tunnelling work is part of the Pink Line, a segment of the Namma Metro project's Phase II, extending from Kalena Agrahara to Nagawara. Rudra began its tunnelling operations in April 2021.

The real challenge

Rudra faced a unique challenge last year in September when it was trapped in a large garbage heap in a Lakkasandra landfill.

A Bangalore Metro Rail Corporation Limited (BMRCL) source, explaining to DH how they solved the problem and surged ahead, said: “The area under the landfill was soft. As soon as we started the tunnelling, there was a settlement in the ground and the soil was not holding because it was semi-liquid. We replaced the area with concrete.”

Blindsided by the challenge, the authorities took some time to get a hang of the problem, design a solution and implement it on the ground. After clearing the stretch, it was a smooth sail for BMRCL.

Rudra was then relaunched from Lakkasandra in August. The source explained, "The machine has now completed three drives totalling 2,077 meters. This involved the journey from the South Ramp to the Dairy Circle station (600 metres), the relaunch towards Lakkasandra station (746 metres), and the final leg to the Langford station (718 metres). These three drives took approximately two-and-a-half years to complete."

The source noted that Bengaluru's geology presented a mix of hard rock, soil, and boulders, but favourable stretches with no buildings eased the work.

The team also implemented preventive measures, such as regularly replacing cutters, to maintain efficiency in the tunnelling process.

Facts about Rudra

TBM procured from Herrenknetch, Germany

Launched on July 14, 2023

Tunnel boring from Lakkasandra station to Langford Town station

Rudra earlier completed 613.2 m between South Ramp and Dairy Circle station and 746.2 m between Dairy Circle station and Lakkasandra station.

718 m: Total length of tunnel drive 

100 days: How long it took to complete the tunneling