The National Green Tribunal’s decision to halt tree felling for Bengaluru’s proposed Hebbal short tunnel has turned a transport project into a wider test of how the city evaluates congestion, environmental damage and infrastructure costs. The southern zone bench in Chennai issued the order on October 16 after a legal challenge by the Mangaluru-based Aranya Parisara Mathu Havamana Badalavane Sangha. The case is scheduled to return to the tribunal on December 15.
The immediate consequence is clear: authorities cannot cut trees along the proposed tunnel route while the legal challenge is pending. The order covers the project length, according to Benedict Fernandes, secretary of the petitioning organisation. The petitioners had asked the tribunal to prevent felling, cutting or removal of trees without the necessary legal clearances.
The scale of the proposed clearance is at the centre of the dispute. The Greater Bengaluru Authority has received more than 1,500 objections to the removal of 1,128 trees. A vegetation survey identified more than 1,400 trees along the route, while the official estimate currently indicates that 1,128 trees would be affected over roughly a two-kilometre stretch. The trees include heritage, native, flowering and fruiting species in Hebbal tree park, areas around Hebbal Lake, the veterinary college campus, University of Agricultural Sciences staff quarters and adjoining locations.
That difference between the survey count and the official estimate is not merely a matter of arithmetic. It shows how the environmental footprint of a linear urban project can change depending on what is counted, which boundaries are used and at what stage the assessment is carried out. The Indian Express report also noted that the authority had faced criticism for not uploading the list of proposed tree species when it invited objections on September 20 with a 10-day response period.
The environmental challenge extends beyond the trees themselves. The petition raises concerns about Hebbal Lake, nearby wetlands, groundwater and natural drainage systems. It argues that excavation, noise, dust, pollution and habitat destruction could damage biodiversity and permanently alter the local microclimate. These concerns place the tunnel within a larger urban systems question: whether transport infrastructure can be assessed separately from the water, vegetation and drainage networks through which it is built.
The proposed 2.2-kilometre tunnel would connect Esteem Mall Junction in Hebbal with the veterinary college on Bellary Road. Construction has already started on vacant land within the college campus, but the tribunal’s direction prevents tree removal along the route while the matter remains before it. The order therefore creates a distinction between work that can proceed on already available land and work dependent on clearing the contested corridor.
The project’s transport rationale is also disputed. The petitioners argue that the tunnel would not eliminate congestion but shift traffic towards the veterinary college and Mekhri Circle. That concern is supported by an August report from the Indian Institute of Science’s Sustainable Transportation Lab, which said the tunnel would not resolve congestion but relocate it to new choke points. The report further estimated that the tunnel could cost taxpayers roughly six times more than an equivalent metro alternative.
The evidence presented in the report shows that the disagreement is not simply between a road project and environmental campaigners. It includes a conflict between competing technical assessments. Professor Archak Mittal of IIT Bombay supported the project in a study titled “Integrated Traffic Microsimulation Study”. The IISc Sustainable Transportation Lab, however, described that report as biased and not scientific. The available material does not establish how the dispute between the two assessments will be resolved, but it makes the modelling assumptions central to the project’s future.
One specific modelling issue concerns the relationship between the proposed tunnel and the existing road. The IISc lab stated that the arrival of the flyover would reduce the existing road’s capacity because of the footprint of the flyover piers. It also said the model used to assess project performance did not account for that reduction. If the road space available after construction differs from the space assumed in the model, projections of traffic movement and congestion would be difficult to compare without revisiting the underlying assumptions.
This is the institutional problem exposed by the dispute. The Greater Bengaluru Authority is responsible for receiving objections and advancing the project, while the tribunal is examining the legality of tree removal and environmental concerns. Technical institutions are producing different assessments of traffic performance and cost. Residents and environmental groups are using objections, petitions and signature campaigns to challenge the project’s stated benefits. The project is therefore moving through several decision-making systems at once, each asking a different question about the same tunnel.
The public objections indicate that the project has generated concern beyond the immediate construction footprint. A Change.org campaign was launched by urban mobility expert Satya Arikutharam, Bangalore Environment Trust trustee Dattatraya T Devare, Citizen Action Forum representative N S Mukunda, and activist and photojournalist Puneet Sachdev. The number of objections does not by itself settle the technical or legal issues, but it demonstrates that the route has become a significant civic concern.
The tunnel debate also highlights the limits of evaluating urban mobility through travel time alone. A project may be presented as a way to move vehicles through a constrained corridor, but its performance depends on what happens at the exits, how adjoining roads absorb traffic, and whether connected infrastructure reduces or creates new bottlenecks. The petition and the IISc report both focus on the possibility that congestion will move rather than disappear. That question is especially important for a short tunnel linking two already active junctions.
The cost comparison with a metro alternative adds another layer. The report supplied by the Indian Express attributes the estimate of a tunnel costing roughly six times more than an equivalent metro alternative to the IISc lab. The available material does not provide the underlying project costs, the definition of the metro alternative or the assumptions behind the comparison. It does, however, establish that public expenditure is part of the technical dispute, alongside traffic capacity and environmental impact.
The NGT proceedings now provide the next formal checkpoint. Until the December 15 hearing, tree removal along the project route is barred under the tribunal’s direction. The unresolved questions include whether the required legal clearances exist, how the affected trees and surrounding ecological systems have been assessed, whether the traffic models account for the flyover’s impact on existing road capacity, and how the competing studies should be weighed.
What the order confirms is that the Hebbal tunnel is no longer only a construction proposal awaiting implementation. It is a contested urban intervention whose environmental footprint, congestion benefits, cost and technical justification are being questioned through legal and institutional channels. What remains unsettled is whether the project can demonstrate that the traffic problem it targets will be reduced rather than transferred, and whether its environmental and financial costs have been adequately accounted for before more of the corridor is altered.
