Officials from Bengaluru Smart Infrastructure (B-SMILE) claim the reduced timeline is achievable through the deployment of advanced TBMs, each capable of boring a minimum of 200 metres per month—more than double the previous estimate. The overall project duration has also been reduced from 61 months to 50 months in the final DPR.

“We initially considered six TBMs with a cutting speed of 90 metres per month, but that made the process too lengthy,” said B S Prahallad, Director, B-SMILE. “Switching to eight high-speed machines allows us to complete 32 km of tunnelling in two years under optimal conditions.”

However, experts have raised concerns over the ambitious schedule. Ashish Verma, professor at IISc, noted that tunnel excavation is fraught with unpredictable ground conditions, which the DPR may not have adequately accounted for. “Based on Bengaluru’s tunnelling history, unexpected geological challenges and bureaucratic delays are frequent,” he said.

Independent mobility expert Satya Arikutharam criticised the DPR’s assumptions, questioning the cost implications of using additional TBMs and the lack of realism in the projected timeline. “Unrealistic deadlines will deter serious contractors from bidding,” he warned.

New source: New Indian Express