BENGALURU: The proposed 2.2-km short tunnel between Hebbal flyover junction and Veterinary College may merely shift congestion to the tunnel’s entry and exit points, and face flooding risks near Hebbal Lake, according to a traffic impact study by Indian Institute of Science (IISc). The study, prepared by IISc Sustainable Transportation Lab (IST Lab) under Professor Ashish Verma, assessed the proposed six-lane cut and cover tunnel against a Business-as-Usual scenario, and an underground Metro alternative for 2027, 2031 and 2041.
According to the report, the tunnel would reduce congestion at Hebbal Junction, but severe congestion would persist before the tunnel entrance and after its exit.
The study predicts new bottlenecks near Veterinary College and Esteem Mall, where existing surface roads would continue to carry high traffic volumes. The report flags a 60-metre radius curve near the Esteem Mall exit, where the operating speed could fall from 60kmph to 40kmph. The study says speed reduction could lower road capacity and create queues, potentially undermining the tunnel’s primary objective.
The report also raises concerns over the project’s cost. Its capital-cost analysis estimates the cost at Rs 5.23 per passenger for the tunnel, compared with Rs 0.86 per passenger for the underground Metro. It concludes that the tunnel would require about six times more taxpayer funding for comparable benefits.
The study has also flagged discrepancies in the tunnel’s Detailed Project Report (DPR), alleging that it uses lower-than-standard road capacities and arbitrary traffic diversion estimates of 50-80 per cent, potentially inflating projected congestion levels.
The proposed tunnel lies in a low-lying area near Hebbal Lake. The study warns that the location could be vulnerable to flooding during rain and notes that the DPR does not clearly address flood scenarios or evacuation plans. It also flags potential geotechnical risks to foundations of the existing flyover due to limited soil support between the lake boundary and the flyover piers.
The study recommends prioritising mass rapid transit systems, arguing that the Metro would provide more sustained network-wide congestion reduction, while reducing dependence on private vehicles, fuel consumption and emissions.