Complex sentence: The growth of Navi Mumbai was aimed at decongesting Mumbai in respect of both population and commercial activities by shifting industries, market, and office activities making the new city sustainable physically, economically, and environmentally.
Split into simpler sentences: The growth of Navi Mumbai was aimed at decongesting Mumbai in respect to both population and commercial activities by shifting industry, market, and office activities. This would make the new city sustainable physically, economically, and environmentally.