Mumbai, known for its limited space and congested areas, is witnessing a vertical growth trend that is reaching unprecedented heights. Developers in the city have been taking advantage of a virtually unlimited floor space index (FSI) available in certain rehabilitation housing schemes, allowing them to construct taller and taller buildings.

A prime example of this vertical growth is taking place behind Bhatia Hospital in a narrow lane called Javji Dadaji Marg in south Mumbai. The location, which previously housed the old Chikalwadi chawls, is now witnessing the construction of India's tallest residential twin towers on a two-acre plot. Under Development Control Regulation 33 (9) meant for cluster redevelopment, the FSI is set at an impressive 10, while the average FSI in the island city is around 3. This means that on a 1,000 square meter plot, a builder can construct 10,000 square meters of space.

The twin towers, named Aaradhya Avaan, are expected to reach a height of 312 meters and will comprise 18 podiums and 61 habitable floors upon completion. Currently, the tallest residential building in Mumbai is the Minerva, standing at 306 meters in Mahalaxmi.

The availability of such high FSI raises concerns about whether Mumbai's infrastructure can handle the load of these massive constructions. Kedarnath Rao Ghorpade, an environmental sustainability planner and former chief planner of the Mumbai Metropolitan Region Development Authority, describes Mumbai as an "urban planning experiment laboratory" when it comes to increasing land potential.

Manan Shah, the Managing Director of Man Infraconstruction, which is redeveloping the old Chikalwadi chawls, acknowledges the significance of the high FSI for their project's feasibility. As part of the redevelopment, the chawl residents will be relocated to a separate tower on a portion of the plot, free of cost. The total construction on the two-acre plot will cover a massive 13 lakh square feet.

The increase in FSI and the subsequent vertical growth can be attributed to the development control and promotion regulations implemented to meet the rising demand for additional floor space. However, there are concerns about sustainability and the lack of supporting infrastructure to accommodate these developments.

Housing expert Chandrashekhar Prabhu warns about the negative consequences of high FSI, such as the abuse of building materials, increased construction and maintenance costs, concretization of open spaces, and poor planning. He stresses that high FSI leads to incredibly dense living conditions, which can have disastrous effects on the well-being of citizens.

Architect Manoj Daisaria counters these concerns by claiming that the Brihanmumbai Municipal Corporation (BMC) conducted a detailed study of civic infrastructure related to water, sewerage, and stormwater drains before finalizing the new Development Control and Promotion Regulation (DCPR-2034). According to Daisaria, the study concluded that Mumbai's infrastructure could handle the increased load, especially with the implementation of mass transport systems like metros, monorails, and coastal roads, which aim to alleviate traffic congestion in the future.

Comparisons are often made to cities like Manhattan and Hong Kong, where high FSI allows for the construction of some of the world's tallest towers. However, it is important to note that these cities have stringent building rules, with a significant portion of land dedicated to open spaces for public amenities. Critical impact assessments are conducted before approving plans, ensuring that the overall impact on the city is carefully evaluated. Additionally, high FSI in these cities is primarily sanctioned in commercial zones, with more restrictive regulations in residential zones due to citizen involvement.

In Mumbai, the lack of proper zoning laws and frequent amendments to the city's development plan have contributed to haphazard and rampant development, particularly in congested areas. Zoning plays a crucial role in shaping the city, regulating building size, population density, and land usage. Experts emphasize the need for comprehensive and thoughtful planning to ensure sustainable growth and the well-being of Mumbai's residents.

This story was earlier published in ET Realty