In a setback to the Karnataka government and Deputy Chief Minister D.K. Shivakumar’s ambitious Bengaluru Tunnel Road Project, an expert committee appointed by the Karnataka Urban Development Department has found the Detailed Project Report (DPR) to be hastily prepared and technically deficient, relying on only four soil test points for an undertaking of this magnitude.

Headed by Siddanagouda Hegaraddi, Executive Director (Civil) of Bangalore Metro Rail Corporation Ltd (BMRCL), the committee also raised serious environmental concerns over a proposed tunnel shaft within the Lalbagh Botanical Garden, calling it ecologically unsustainable and recommending that its location be reconsidered immediately.

Weak Traffic Analysis and Unclear Justification

The panel questioned the very necessity of the tunnel, noting that its proposed alignment runs almost parallel to the Namma Metro’s north–south corridor. The committee observed that both projects aim to serve the same route and that, without reliable data on how many commuters would switch from private vehicles to public transport, the tunnel’s justification remains unverified.

“The general apprehension of stakeholders is that the tunnel project will become redundant, as it mirrors the metro alignment. This concern could not be addressed due to the absence of peak-hour traffic data, modal share, and projections,” the report noted.

The panel described the DPR’s traffic study as “particularly weak”, stating that it was based solely on secondary data and assumptions with no field surveys or primary measurements undertaken. It also highlighted missing information such as mode-wise commuter distribution, projected peak-hour traffic, and expected modal shifts to BMTC buses, metro, or suburban rail.

Flaws in Technical Design

The committee criticised the DPR for basing lane configurations on Level of Service (LoS) rather than Passenger Car Unit (PCU) data, which measures real traffic flow. It recommended that lane requirements be recalculated based on PCU data while factoring in potential shifts to public transport.

It also flagged the placement of entry and exit ramps, warning that they could intensify congestion near junctions where tunnel and surface traffic merge — particularly around Palace Grounds and Mehkri Circle. The panel advised a minimum two-lane configuration for ramps to ensure safe traffic movement.

Another key issue identified was the “horizon year” of traffic projection. The DPR projects demand only up to 2041, just ten years after expected completion, instead of the standard 25-year planning horizon used for large-scale infrastructure. The panel said that either the projection period should be extended or the six-lane (3+3) plan scaled down to match actual data, which only supports four lanes (2+2).

Echoing DULT’s Earlier Concerns

Urban mobility expert Sathya Arikutharam, who compared the expert committee’s findings with those of the Directorate of Urban Land Transport (DULT), said both reached similar conclusions — that the Tunnel Road Project lacks a clear transport, strategic, or environmental basis.

DULT’s November 2024 review had already warned that the proposed tunnel contradicted Bengaluru’s Comprehensive Mobility Plan (CMP) and Climate Action Plan, recommending shorter tunnel segments instead. However, the Bruhat Bengaluru Mahanagara Palike (BBMP) proceeded to commission the DPR even before the Bengaluru Metropolitan Land Transport Authority (BMLTA) had completed its review.

Both DULT and the expert committee found that no primary traffic surveys or real-time data collection were carried out, calling into question the scientific validity of the DPR.