The Chennai Mass Rapid Transit System, commonly referred to as Chennai MRTS, is a metropolitan rail transit system in Chennai, India. It is operated by Southern Railway of the state-owned Indian Railways. Opened in 1995, it was the first elevated railway line in India. The railway line runs from Chennai Beach to St. Thomas Mount, covering a distance of with 21 stations and is integrated with the wider Chennai suburban railway network.

While the suburban railway has been operational in Madras since 1931, the Planning Commission of Government of India formed a research group to recommend development of transportation in major cities including Madras in 1965. The Madras Area Transportation Study Unit identified eight transport corridors including the north–southeastern rail corridor along the Buckingham Canal. The Government of India approved a Mass Rapid Transit System for the southern section in 1983–84 with the project to be implemented in four phases. The project was implemented by the Ministry of Railways and construction began in 1991. The first phase from Madras Beach to Chepauk was completed in 1995 with further extension to Thirumayilai in 1997. Part of second phase from Thirumayilai to Thiruvanmiyur was completed in 2004 with further extension to Velachery in 2007. The planned extension from Velachery to St. Thomas Mount was completed in March 2026, after repeated delays.

The Chennai MRTS line is largely elevated with at-grade sections at its terminals. The line runs at-grade initially till Park Town, parallel to the suburban railway network. It becomes elevated thereon, roughly following the course of the Buckingham Canal and running parallel to the Coromandel Coast till Thiruvanmiyur before deviating west towards Velachery. It uses the same broad gauge (5 ft 6in) as the suburban system, thus allowing the movements of trains between the existing suburban lines and the MRTS. The Chennai MRTS uses 9-car electrical multiple unit (EMU) train sets. The trains use 25 kV overhead catenary for traction. The coaches are manufactured by the Integral Coach Factory, Chennai. The coaches are not air-conditioned and are equipped with first-class and second-class passenger seating.

, the system has a daily ridership of 100,000. With the implementation of the Chennai Metro Rail starting in 2015 and planned expansion of the same, further expansion of the MRTS system was put on hold in 2017, with the plans for the MRTS system to be taken over by Chennai Metro Rail Limited. In 2022, the Southern Railway of Indian Railways gave an in-principle approval for the take-over under which the coaches, stations and other infrastructure will be upgraded on par with the Chennai Metro.

Background The Chennai Suburban Railway started operations in 1931 on a single electrified line from Chennai Beach to Tambaram. Suburban services commenced on the second line between Chennai Central and Gummidipoondi in 1985 the third line from Central towards Arakkonam was added later. In 1965, the Planning Commission formed a group to study the suitability of the existing transportation network, to ascertain the viability of various ways of transportation and advocate plans for the expansion of transportation in metropolitan cities including Madras.

Planning Surveys were conducted to supplement the existing transport infrastructure in Madras, such as the Madras Area Transportation Study (1968), Integrated Transport Plan (1977) and Madras Route Rationalisation Study (1986). The Madras Area Transportation Study Unit (MATSU) identified eight important transport corridors including the north–southeastern rail corridor connecting Kasturba Nagar and Manali Road. The study suggested the implementation of a rail-based Mass Rapid Transit System (MRTS) on the southern section of the line along the Buckingham Canal, connecting to the existent suburban system. The system was envisaged as a loop line connecting Chennai Beach and Tiruvottiyur.

Since the planned railway line would pass through congested parts of the city, an elevated rail system was selected, to avoid land acquisition problems. The project was intended to be implemented in four phases: Chennai Beach to Thirumayilai, Tirumayilai to St. Thomas Mount, St. Thomas Mount to Villivakkam and Villivakkam to Ennore.

Construction and opening

Phase I The project was sanctioned for implementation by the Ministry of Railways, Government of India in 1983-84. After multiple delays, construction began in 1991 and part of the first phase from Chennai Beach to Chepauk was completed in 1995. It became operational on 16 November 1995 and was the first operational elevated railway line in India. The line was extended to Thirumayilai in 1997. The cost of construction of the first phase between Chennai Beach and Thirumayilai, estimated to be , was fully financed by the Government of India. The first phase was projected to serve about 600,000 passengers per day.

Phase II RITES conducted further studies in 1987 and 1994 on the effectiveness of the existing public transport system for the growing population. The studies proposed further expansion of the MRTS line. In 1998, the Railway Board sanctioned Phase II of the project from Thirumayilai to Velachery. Part of the Phase II line from Thirumaylai to Thiruvanmiyur was opened on 26 January 2004. It initially consisted of a single line of track for both forward and return journeys. On 19 November 2007, the network was extended from Thiruvanmiyur to Velachery. While the state government gave only the required land for the first phase, it contributed two-thirds of the total project cost of for the second phase.

Phase II extension The construction for the extended second phase of the project connecting Velachery with St. Thomas Mount started in 2008. It was planned at an estimated cost of with the central government bearing two-thirds of the cost and the state government bearing the rest. The initial planned alignment was altered subsequently and necessitated the demolition of over 70 residential units, which led to protests by the locals. In the Government of India's annual Railway Budget of 2012, it was announced that the line would be commissioned in 2013. In October 2012, Chennai Metropolitan Development Authority (CMDA) resumed the land acquisition for the proposed extension after the Madras High Court vacated its earlier stay order on the same. While land acquisition was completed for the construction of majority of the line by April 2013, there were further delays in acquiring land for about of the stretch and the construction of Puzhuthivakkam station. , the construction of about of the proposed extension was complete.

In May 2014, the High Court ruled that compensation be paid as per newly enacted Land Acquisition Act 2013 on the cases filed by the land owners. In March 2016, the Southern Railway stated that the final phase of the MRTS would take at least 18 months after the state government handed over land to Indian Railways and that it had not yet done so. In 2018, further discussion between the CMDA and the land owners on the compensation to be paid for the land acquisition failed. , the Indian Railways had completed the construction of Adambakkam and Puzhuthivakkam elevated stations, with about of the line pending for construction. In 2019, the Madras High Court directed the CMDA to pay higher compensation to the land owners. However, the CMDA filed a review petition against the order in the Indian Supreme Court.

The Supreme Court ordered fair compensation for the land owners and directed the CMDA to complete the land acquisition by 8 January 2021. In June 2022, officials announced that the land acquisition for the final stretch would be completed in the next three months. In July 2023, the authorities said that the construction will be completed by the end of the month and the line will be commissioned for use within the end of the year. On 18 January 2024, a concrete girder on the stretch collapsed, which was expected to further delay the opening of the line. Multiple revised deadlines to complete the construction of the final phase were not met. After the construction was completed, trial runs were conducted in the first week of March 2026. Commercial service began on the extended section from 14 March 2026.

Future plans The third and fourth phases of the MRTS were initially planned to connect St. Thomas Mount with Villivakkam and Villivakkam with Ennore. The plans have been shelved after the lines overlapped with the proposed extension of the Chennai Metro Rail. In early 2024, a feasibility report was submitted to the state government for a new line from Poonamallee and the planned new airport at Parandur. The line would have 19 stations and is expected to cost .

With the Chennai Metro operational since 2015, the Indian Railways proposed for the MRTS system to be taken over by Chennai Metro Rail Limited in 2017. In July 2018, PwC said that the merger would be expensive, costing around to replace the train-sets and establish other facilities. On 11 May 2022, the Southern Railway zone of the Indian Railways granted in-principle approval for the takeover. , the take over was still pending as the Indian Railway Board had not approved the same.

Infrastructure

Network and lines

The line from Chennai Beach to St. Thomas Mount is largely elevated, with a few at-grade sections along the line. The line runs at-grade for from Chennai Beach to Park Town, alongside the suburban railway line. From the Park Town station, the line becomes elevated and roughly follows the course of the Buckingham Canal, which runs parallel to the Coromandel Coast. The line remains elevated for the alignment of the second phase up to Perungudi, after which it returns to an at-grade section at the Velachery station, after which the final section of the line from Velachery to St. Thomas Mount is again elevated.

+Chennai MRTS networkPhaseLengthRouteStationsOpening DatePhase I-AChennai BeachChepauk516 November 1995Phase I-BChepaukThirumayilai419 October 1997Phase II-AThirumayilaiThiruvanmiyur626 January 2004Phase II-BThiruvanmiyurVelachery319 November 2007Phase II-B ExtensionVelacherySt. Thomas Mount314 March 2026

The route taken by the MRTS line has resulted in the pillars of the elevated section of the railway encroaching the Buckingham Canal. Although the pillars were placed basis the approval of the state government, the government later proposed plans to restore the canal to make it navigable. However, as the MRTS pillars have reduced the canal width, a section of the canal is not navigable, and the pillars block the flow of rainwater discharge.

Track The Chennai MRTS line bears greater resemblance to the suburban railway than a rapid transit line as it uses the same broad gauge (5 ft 6in) as the Chennai Suburban Railway system, allowing the usage of same train-sets across the existing suburban lines and the MRTS. Ballastless track is used in the elevated sections between Tirumayilai and St.Thomas Mount stations. The trains use 25 kV overhead catenary for traction.

Rolling stock

The Chennai MRTS earlier used six-car electrical multiple unit train sets, which was replaced by nine-car train sets in 2021. A nine-car rake typically has three sets of three motor coaches each at the front, the middle and the last with electric motors used to drive the wheels of the train at a stipulated speed. The EMU coaches are manufactured by the Integral Coach Factory in Chennai. The coaches are not air-conditioned and are equipped with two-class (first and second class) passenger seating configuration.

Stations

The MRTS line has 21 stations, and the stations are designed to accommodate six and nine-car train rakes.