Bengaluru Hebbal Traffic: IISc Raises Concerns Over IIT-Bombay Report On Tunnel Project

IISc Bengaluru experts have raised concerns over an IIT-Bombay report on the proposed Hebbal tunnel project. The study has sparked a technical debate over traffic data, methodology and the proposed tunnel and elevated corridor.

Bengaluru’s notorious Hebbal junction, one of the city’s major traffic bottlenecks, is at the centre of a fresh technical debate over two proposed projects aimed at easing congestion. A recent traffic microsimulation study has recommended prioritising the elevated corridor between Mekhri Circle and Veterinary College over the proposed Hebbal short tunnel. However, experts from the Indian Institute of Science (IISc) and road transport planners have raised questions about the study, citing technical inconsistencies, outdated data and methodological concerns.

What The IIT-Bombay Report Says?

Ritwik Projects Private Limited holds the contract for the Hebbal short tunnel and engaged Prof. Archak Mittal of IIT-Bombay to prepare a 26-page technical study. Critics have questioned whether the document titled Integrated Traffic Microsimulation Study - Bangalore: Hebbal Flyover & Hebbal Short Tunnel represents the official position of IIT-Bombay, describing it instead as an individual expert opinion.

The proposed elevated corridor from Mekhri Circle to Veterinary College is 1.78 km long and will have four lanes and four ramps. The short tunnel proposed under the Hebbal junction is 2.22 km long and will have six lanes.

The study does not completely reject the tunnel proposal but states that the tunnel alone may not be sufficient to address Hebbal’s traffic congestion.

The report also flags the absence of an Origin-Destination (O-D) survey in the Detailed Project Report (DPR). It recommends conducting a proper O-D survey, noting that the effectiveness of the tunnel would depend largely on the number of motorists who divert to it.

IISc And Transport Experts Raise Concerns

Prof. Ashish Verma, convenor of IISc’s Sustainable Transportation Lab, and Satyajit Arikutharam, former chief technical adviser at the Directorate of Urban Land Transport (DULT), have raised several concerns about the IIT-Bombay study.

Missing Options And Outdated Data

The study initially proposed examining four scenarios: the existing situation, the elevated corridor, the underground tunnel and a combined model. However, critics point out that the study ultimately assessed only the existing situation and the combined model.

They have also questioned why the study did not account for changes in traffic patterns expected after the new Hebbal flyover ramp becomes operational in January 2026.

Traffic Speed Mismatch

The IIT-Bombay study estimates that vehicles will travel at an average speed of 13.74 kmph during peak hours in 2027. However, the original DPR had estimated the average speed at 4.29 kmph.

Critics have questioned the significant difference between the two estimates and sought an explanation for the change.

No Ramp For Straight-Moving Traffic

The proposed elevated corridor does not include a ramp for vehicles travelling straight towards Windsor Manor. As a result, only vehicles turning from Mekhri Circle would be able to use the elevated corridor, while straight-moving traffic would continue to rely on the existing underpass.

Future Transit Projects Not Considered

Experts have also raised concerns that the study does not adequately account for upcoming transport projects, including the Hebbal-Sarjapur Metro line, the Suburban Rail project and the Yeshwanthpur-KR Puram East-West corridor.

These projects could alter traffic patterns in and around the Hebbal junction once they become operational.

Proposed Changes To Project Design

The study recommends increasing the distance between the proposed tunnel and elevated corridor from 80 metres to 250 metres. Such a change would require modifications to the existing project design, according to the concerns raised by experts.

BDA Defends The Project

Senior BDA officials said IIT-Bombay was engaged to conduct a third-party assessment following concerns raised by members of the public over the project.

The BDA has said it is considering the suggestions made in the study. Officials maintained that both the short tunnel and the elevated corridor would be required to address future traffic demand at Hebbal.

The BDA plans to take up the elevated corridor alongside the tunnel. Preliminary work on the short tunnel has already begun, and the authority aims to complete the project by January 2028.