MUMBAI, Sept. 30 -- The long-awaited Metro Line 8 project, which will provide a direct mass transit link between Mumbai's Chhatrapati Shivaji Maharaj International Airport (CSMIA) and the upcoming Navi Mumbai International Airport (NMIA), has reached a crucial milestone. The detailed project report (DPR) has been submitted to the state government for approval after receiving clearances from both the urban development and finance departments, senior officials confirmed. According to the DPR, the 34.89-km corridor will cost an estimated Rs.23,000 crore and is being planned on a public-private partnership (PPP) model, similar to Mumbai Metro Line 1 (Versova-Ghatkopar). The City and Industrial Development Corporation (Cidco), the nodal agency for the project, has sought 20% viability gap funding (VGF) each from the state and Centre, with the balance investment to come from the private build-operate-transfer (BOT) partner. The line will feature 20 stations-six underground and 14 elevated-with projected daily ridership expected to reach 1,030,000 passengers by 2031. Officials said the corridor will serve as a "seamless connector" across the Mumbai Metropolitan Region (MMR)....