Design flaw on Mumbai Metro 7A could cost Rs 260 crore, delay airport link

A section of the Mumbai Metro Line 7A, which connects Andheri East to Chhatrapati Shivaji Maharaj International Airport, faces potential demolition due to a design flaw discovered during construction. The issue involves a viaduct segment near the Airport Colony station in Vile Parle East, where the structure’s height exceeds permissible limits set by aviation authorities. The estimated cost of rebuilding this part of the project ranges between Rs 250 crore and Rs 260 crore, according to officials with the Mumbai Metropolitan Region Development Authority (MMRDA). The affected stretch spans nearly one kilometre and had already been constructed before the problem was identified. The flaw relates to the overhead electrification (OHE) system, which requires additional vertical space. This requirement was not properly considered during the initial design phase, leading to the current situation where the viaduct stands approximately 2.5 metres higher than allowed under aviation regulations. The discovery of this issue occurred in 2025, when construction on the affected area had reached an advanced stage. Since then, work has been suspended, pending resolution of the problem. The MMRDA has approached the Airports Authority of India (AAI) seeking a relaxation of the height restrictions. However, if such approval is denied, the authority may be forced to dismantle the existing structure and construct a new one that meets the required standards. According to officials, simply reducing the height of the current viaduct might not be viable, as it could disrupt the necessary gradients for safe metro operations. The MMRDA has attributed the oversight to its general consultant, the Systra-CEG-SMCIPL consortium, which was responsible for ensuring compliance with all design and statutory requirements, including those related to aviation. In a statement, Basavaraj MB, Director of Metro Projects at the MMRDA, noted that the consultant failed to highlight the need for extra height for the OHE system at the appropriate stage of planning. The MMRDA is currently waiting for the AAI's final technical report on acceptable height clearances and potential modifications. This development adds further complications to an already delayed project. The 3.4-kilometre corridor connecting Andheri East to the airport was initially slated for completion in 2021. However, multiple setbacks have pushed back the timeline significantly. The airport link, intended to enhance connectivity between the metro network and the international airport, is now likely to face yet another postponement. Any decision to rebuild the affected section would add both time and financial burden to the project. The affected viaduct is located in a critical area near the airport, where strict height limitations apply to ensure unimpeded aircraft movement. The proximity to the airport makes any deviation from the prescribed standards particularly problematic. Aviation authorities typically enforce stringent guidelines to prevent any structures from interfering with flight paths or air traffic control systems. As a result, even minor infractions can lead to serious consequences, necessitating immediate corrective action. The MMRDA is conducting a thorough technical evaluation based on the AAI's findings. Once the report is finalized, the authority will determine whether adjustments can be made to the existing structure or if complete reconstruction is necessary. Until then, the project remains in limbo, with no clear resolution in sight. The incident underscores the complexities involved in large-scale infrastructure projects, especially those operating in highly regulated environments. It highlights the importance of meticulous planning and adherence to regulatory frameworks to avoid costly mistakes. For the MMRDA, the challenge lies in balancing the need for timely completion with the imperative to comply with all legal and safety requirements. The outcome of the ongoing discussions with the AAI will play a crucial role in shaping the future of the Metro 7A project. If the requested relaxation is approved, the existing structure may remain intact, allowing the project to proceed with minimal disruption. Otherwise, the authority may have to bear the substantial costs associated with dismantling and rebuilding the affected section.