The Metro-11 corridor, planned as an extension to Metro-4 from Wadala towards south Mumbai at General Post Office (GPO), may now be partially underground. Once the Central government approves an in-principle agreement between the Mumbai Port Trust (MbPT) and the Mumbai Metropolitan Region Development Authority (MMRDA), this will be the third partially underground Metro corridor in the city.The project had been stalled as the MbPT wanted the corridor to go underground and the MMRDA asked it to bear the extra cost. However, the agencies have now reached an in-principle agreement where the metropolitan authority will be allowed to develop the areas around the station and fund the underground portion. The two agencies are yet to decide exactly which section of the corridor will be underground but it will be mostly in the land owned by the MbPT. Sanjay Bhatia, chairman, MbPT, said, “Since they [MMRDA] are taking it underground, the difference in cost will be covered by giving them the area. It will mostly be near the stations. The decision is in-principle and needs approval from the Central government.” The MMRDA had stated that the cost will be ₹1,000 crore per kilometre if the corridor goes underground instead of ₹300 crore per kilometre for an elevated corridor. A stretch of about 4km will be underground in the port trust area. The port trust is working on a grand plan which looks at unlocking the potential value of the land. RA Rajeev, metropolitan commissioner, said, “Like the other metro corridors, we will undertake transit-oriented development and cross-subsidise the cost.” Metro-11 will be the third partially underground corridor in the city. The other two are Metro-7A (Andheri (E)-Chhatrapati Shivaji International Airport) and Metro-8 (Chhatrapati Shivaji International Airport to the proposed Navi Mumbai International Airport), which will be partially underground.