The Maharashtra government has approved the expansion of Mumbai Metro Line 5 along with a new integrated corridor, Metro Line 5A, forming a combined 34.2-km metro network across the Thane-Bhiwandi-Kalyan-Ulhasnagar belt. The integrated project has been cleared at an estimated cost of ₹18,130.55 crore, according to a government resolution (GR).Metro Line 5 was originally approved in October 2017 as a 24.9-km fully elevated corridor with 17 stations connecting Thane, Bhiwandi and Kalyan, with an initial project cost of ₹8,416.51 crore. The corridor is being developed in two phases.The first phase, covering 11.9 km between Thane and Bhiwandi with six stations, is currently in the final stages of construction. Officials said this stretch progressed faster as it did not face major rehabilitation and resettlement hurdles.However, the second phase from Bhiwandi to Kalyan has been delayed due to encroachments along the alignment, requiring demolition drives by the Bhiwandi municipal corporation. The 10.475-km stretch, also planned with six stations, has undergone multiple design changes and cost revisions.In June 2023, a portion of the alignment between Durgadi and Kalyan was shifted from elevated to underground, leading to a cost escalation of ₹1,427 crore. A further review in June 2025 resulted in additional modifications, with the state deciding to make the corridor partially underground between Dhamankar Naka and Temghar. Following these changes, the revised cost of the second phase has been estimated at ₹7,326.13 crore.In a major change to the original plan, the state has curtailed Line 5’s alignment, with the corridor now set to terminate at Durgadi instead of extending up to Kalyan. To ensure continued connectivity, the government has approved Metro Line 5A as an extension of the network.The 11.83-km Metro Line 5A will run from Durgadi via Aadharwadi and Khadakpada to Kalyan, with a further extension proposed towards Ulhasnagar. The corridor will have seven stations and is estimated to cost around ₹4,063 crore.Together, Line 5 and Line 5A will form an integrated metro system with 19 stations and an interchange at Durgadi. The plan also includes a double-decker structure combining a flyover and metro line between Ranjnoli Junction and Durgadi Chowk to reduce congestion in Bhiwandi. Officials said the project incorporates transit-oriented development along the corridor and commercial utilisation of station spaces to improve overall viability.