Bengaluru’s proposed 16.7-km twin tunnel road, often touted as a miraculous solution to the city’s crippling traffic, might actually do more harm than good. A new modeling study warns that this ambitious project could deter commuters from using the metro and bus systems, significantly escalate vehicular pollution, and still leave vital roads like the Outer Ring Road (ORR) gridlocked.
Led by Ashish Verma from the Centre for Infrastructure, Sustainable Transportation, and Urban Planning (CiSTUP) at the Indian Institute of Science (IISc), the research simulated travel demand and traffic volumes under three distinct scenarios: a tolled tunnel road, a toll-free tunnel road, and a scenario based on commuter surveys predicting traffic shifts. These projections spanned seven future years, from 2030 to 2060, to thoroughly assess the project’s long-term performance and its extensive impact on both the ORR and public transport networks.
The study found that a tolled tunnel road would see extremely low usage. By 2060, even its busiest section would only carry approximately 11,351 vehicles daily. With tolls estimated at around ₹300 per trip, a daily commuter making two trips would face monthly expenses of nearly ₹18,000. Such a cost would be prohibitive for middle and lower-income families, and even substantial for IT professionals. Consequently, the tunnel would predominantly serve wealthier commuters.
Removing tolls led to a marginal increase in usage, but still fell considerably short of the tunnel’s design capacity. In the toll-free scenario, the busiest stretch is predicted to carry about 17,841 vehicles per day by 2060. However, a potential shift scenario, based on commuter surveys, projected a daily usage of over 50,000 cars, motor two-wheelers (MTWs), and buses by 2045-2060. This ‘success’ comes with a catch: commuters wouldn’t just be shifting from private cars, but also from existing bus and metro services. The survey indicated that up to 40% of car and two-wheeler users, and roughly a third of bus riders, would opt for the tunnel. In stark contrast, the metro would only attract 1.5%–6% of commuters from these groups. The study explicitly states that the tunnel would undermine public transport systems rather than enhancing them.
Persistent ORR Congestion
Crucially, the tunnel is unlikely to ease congestion on the ORR, Bengaluru’s most vital traffic artery. Across all simulated scenarios, several stretches of the ORR consistently showed volume-to-capacity (V/C) ratios significantly above 1.0, indicating that traffic demand would far exceed the road’s capacity. A V/C ratio above 1.0 is a clear indicator of severe traffic congestion.
This finding is particularly concerning given that extensive Metro lines are already planned along the ORR. Phase-3 of Namma Metro, approved by the Karnataka government, includes a 32.15-km stretch from Hebbal to JP Nagar via Goraguntepalya, Magadi Road, Mysuru Road, and Kanakapura Road, following the western ORR. Additionally, a 12.5-km section from Hosahalli to Kadabagere on Magadi Road is also part of this expansion. These metro projects are specifically designed to alleviate ORR congestion by encouraging a shift towards mass transit. The tunnel road, however, risks drawing commuters back to private vehicles, thereby nullifying the benefits of these considerable public investments.
For instance, in the tolled scenario, one ORR section was projected to manage over 1.83 lakh vehicles with a V/C ratio of 2.02 in 2055, signaling extreme congestion. Even without tolls, the same stretch recorded a V/C ratio of 1.99 by 2060. While the traffic-shift scenario showed minor improvements, widespread congestion would still persist across most links.
Increased Emission Footprints
The study also highlights the tunnel’s substantial environmental repercussions. Under scenarios incorporating Metro and Mass Rapid Transit System (MRTS) expansion for 2041, the presence of the tunnel and a double-decker road consistently led to an increase in emissions across all pollutant types.