Southern Railway has forwarded a draft memorandum of understanding to the Railway Board, advancing the planned takeover of the Mass Rapid Transit System by Chennai Metro Rail Limited (CMRL). The submission follows an in-principle nod from the Railway Board in July 2025 and advances the proposal to the final administrative stage. The move represents a decisive step towards integrating the city’s two major rail networks to improve connectivity and modernise infrastructure. Under the proposed arrangement CMRL will assume operational control of the MRTS while Southern Railway will provide maintenance support during a two-year transition period. The Tamil Nadu government will sign the agreement with Southern Railway once the Railway Board grants final clearance and is expected to reclaim substantial land parcels associated with the MRTS corridor. The state has signalled a firm commitment to funding upgrades and is open to support from multilateral agencies. Estimates place the required investment at about Rs 40–42 billion (bn) for station redevelopment, acquisition of new rolling stock, implementation of a unified ticketing system and improvements to passenger amenities. The plan includes upgrading the Chennai Beach–Velachery elevated corridor to metro standards and introducing modern air-conditioned coaches to enhance commuter comfort. Phased capital expenditure and coordinated project management will be central to delivery. The integration is expected to deliver seamless interchange between metro and MRTS services, a unified fare structure and materially improved frequency and reliability for commuters. Upgraded stations will focus on accessibility, safety and better passenger facilities while a unified operations framework should simplify journey planning. Officials project that the full transition will be completed by 2027–2028. The MRTS has operated as a standalone system for over three decades and its assimilation into CMRL is seen as a long-awaited reform to address chronic underutilisation. Stakeholders believe the merger will unlock the corridor’s potential as a vital north–south artery in Chennai’s public transport ecosystem and support sustainable urban mobility. The development is a meaningful gain for commuters and a milestone in the city’s efforts to create a unified high-capacity rail network.