Bengaluru’s Tunnel Road Project Under Scrutiny

Karnataka’s plan to develop an 18.5 km underground tunnel connecting Silk Board Junction and Hebbal Junction has encountered a major review phase after a government-appointed expert panel identified several technical, environmental, and financial shortcomings in the Detailed Project Report (DPR). The panel has recommended a comprehensive revision of the report before further progress on the project.

The five-member committee identified several technical, financial, and environmental deficiencies in the DPR, prepared by Rodic Consultants Private Limited. The major flaws include:

1. Insufficient Geotechnical Investigation: The DPR used data from only four soil-test boreholes, prompting calls for wider soil and rock testing, including Electrical Resistivity Tomography (ERT) surveys to map groundwater.
2. Environmental Impact: The review flagged environmental challenges related to the proposed location of a tunnel shaft within ecologically sensitive zones, terming it unsuitable. It also identified gaps in the stormwater drainage plan, which lacked hydraulic analysis and did not adequately address natural water flow diversions along the proposed alignment.
3. Alignment and Traffic Assessment Issues: The proposed tunnel alignment has been found to overlap existing public transport corridors, raising questions about its necessity and long-term utility. Traffic projections in the DPR were also deemed overestimated, as they did not factor in commuter transitions to mass transit systems such as metro and bus networks. Additionally, a mismatch was noted between the proposed 3+3 lane configuration and the project horizon year of 2041, which is relatively close to the expected completion timeline. The panel suggested reconsidering the design to a 2+2 lane configuration for better cost-efficiency and engineering relevance.
4. Costing and Design Observations: Concerns were raised regarding the cost estimation process, which requires a more detailed and transparent methodology, including multiple supplier quotations and clear breakdowns for land acquisition, utilities, and toll infrastructure. The design of entry and exit ramps, particularly near major intersections, also requires re-evaluation to prevent traffic congestion and safety risks.
5. Data Accuracy and Documentation: Certain inconsistencies and non-contextual references were observed in the documentation, indicating the need for enhanced data validation and quality assurance. The committee has directed that the revised DPR include verified data, localised analyses, and cross-referenced technical studies to ensure the integrity of the planning process.

With the expert committee calling for a complete revision of the DPR, the tunnel project faces potential delays and cost escalations. The government has yet to take a final decision on the committee’s recommendations. While the project holds promise for transforming Bengaluru’s mobility landscape, inadequate technical validation, nontransparent cost assessments risk, and environmental safeguards reduce it to an expensive experiment.

This underscores the need for robust data integrity, coordinated institutional oversight, and environmental compliance, ensuring that future urban mobility initiatives remain both visionary and sustainable.