The Mumbai Metropolitan Region Development Authority (MMRDA) has solidified plans for the extension of Mumbai Metro?s Line-9 (Red Line) by 4.9 km to its newly identified train maintenance depot in Dongri, Thane District. This extension, an addition to the existing Mumbai Metro Line-2B?s expansion to Cheeta Camp, is a significant development. On September 18, MMRDA formally submitted an application for Coastal Regulation Zone (CRZ) clearance for the Line-9 extension to Dongri Depot to the Ministry of Environment, Forest, and Climate Change. This proposed extension, spanning approximately 4.9 km from Subhash Chandra Bose Ground Station, will include two new elevated stations at Murdha and Rai Goan on Uttan Road. The Dongri Depot will be constructed to accommodate the maintenance of BEML trains for the entire Red Line, connecting Dongri, Mira Bhayandar, Dahisar East, Gundavali, and CSIA Terminal 2. The depot will be situated on a 41.36-hectare land on a hillock. While most of the land is unaffected by CRZ, a few sections of the extended alignment fall under CRZ IA (50M Mangrove Buffer), CRZ IB, and CRZ-II area. According to MMRDA's environmental impact assessment (EIA) report, 4100/4825m of this extension?s main-line falls under CRZ, with specific areas designated for pier construction. MMRDA?s CRZ application is currently under examination, having undergone scrutiny by Maharashtra?s Coastal Zone Management Authority between September 18 to 27. Further clarifications have been requested through an official Essential Details Sought (EDS) letter. The construction of this extension is crucial for Line-9, as it will relieve pressure on Charkop Depot, shared with the Yellow Line, enabling high-frequency train operations. The proposed Dongri Depot layout includes workshop and stabling lines of 210 m length, capable of handling 8-coach trains. Considering the necessary approvals, funding, and bidding processes, construction on this extension is anticipated to commence no earlier than mid-2025. Once completed, the city?s Red Line will span a total of 35.95 km, consisting of four sections: the 4.9 km Line-9 extension from Dongri Depot to Subhash Chandra Bose Ground, the 11.38 km Line-9 from Subhash Chandra Bose Ground to Dahisar East, the 16.5 km Line-7 from Dahisar East to Gundavali, and the 3.17 km Line-7A from Gundavali to CSIA Terminal 2.