Bengaluru Tunnel Road DPR Slashes Tunnelling Time to 24 Months Experts Question Feasibility

The final Detailed Project Report (DPR) for Bengaluru’s ambitious Tunnel Road project has significantly reduced the tunnelling timeline from 33 to 24 months, promising overall project completion within 50 months, down from the earlier 61-month estimate.

This reduction, officials claim, is made possible by deploying eight high-speed Tunnel Boring Machines (TBMs), instead of the six medium-speed TBMs originally proposed. “Each high-speed TBM can cut a minimum of 200 metres per month, or 2.4 km a year. With eight machines, we can achieve over 32 km of tunnel boring in two years,” said B-SMILE Director BS Prahallad.

The ₹13,000-crore Tunnel Road project proposes to bore through 16.7 km each on both sides, totalling around 33.4 km. The move to high-speed TBMs aims to accelerate the core tunnelling work without extending the project duration, which remains a major concern given Bengaluru’s past infrastructure delays.

However, experts have cast serious doubts over the revised timeline. Ashish Verma, professor at IISc, cautioned that unpredictable geological conditions—like hard rock and water ingress—can disrupt even the best-laid plans. “Such uncertainties are rarely accounted for realistically,” he said.

Independent mobility expert Satya Arikutharam was more critical. “If adding two TBMs saves nine months, what stops them from adding two more and claiming it’ll be done in a year? This projection is arbitrary and risks deterring credible contractors from bidding due to unrealistic expectations,” he said, also raising concerns over cost implications.

As Bengaluru chases fast-tracked infrastructure to ease its notorious traffic, the real test will be how well technology, planning, and ground realities align on a project of this scale.