The Chennai Metro is a rapid transit system serving the city of Chennai, India. It is operated by Chennai Metro Rail Limited, a joint venture between the Government of India and the Government of Tamil Nadu. As of December 2025, the network consists of two operational lines spanning and has 41 underground and elevated stations. The system runs on standard gauge and is powered by overhead electric lines.
Plans for a metro rail system for Chennai started in 2007–08 with construction commencing in February 2009. Test runs began in 2014, and the first segment of the metro between the Alandur and Koyambedu stations on the Green Line began operations on 29 June 2015. On 21 September 2016, operations on the Blue Line commenced between Chennai Airport and Little Mount. The underground stretch from AG-DMS to Washermanpet of the Blue Line opened on 10 February 2019, completing the first phase. Additionally, The Chennai Metro is the first metro system in India to operate an Inter-Corridor Line system.
As a part of the second phase, three more lines covering a length of are planned and are under construction. The Chennai Mass Rapid Transit System (MRTS), operated by the Indian Railways, is planned to be incorporated into the Chennai Metro. A light rail has been proposed to connect Tambaram on the Chennai suburban rail network with Velachery on the MRTS. Further extensions are also planned for the three lines under construction.
Background A single electrified line from Chennai Beach to Tambaram began operations in 1931 as part of the Chennai Suburban Railway. Two other rail lines were subsequently built, connecting Chennai Central to Gummidipoondi and Tiruvallur in 1979. In 1965, the Planning Commission evaluated the capacity of the transportation network in major metropolitan cities including Madras, and developed plans for further expansion of transportation amenities. As a result, an initial stretch of the Chennai Mass Rapid Transit System (MRTS) between Chennai Beach and Chepauk opened in 1995 – the first elevated rail line in India. The MRTS later extended to Thirumayilai in 1997, to Thiruvanmiyur in 2004, to Velachery in 2007, and St. Thomas Mount in 2026. In 2006, a modern metro rail system for Chennai was planned, to be modeled after the Delhi Metro.
Planning and construction Phase I
The Delhi Metro Rail Corporation was tasked to prepare a project report for the implementation of a metro rail system in Chennai. The Government of Tamil Nadu approved the first phase of the project in November 2007. The first phase was planned with two lines covering with being underground. The first corridor would connect Washermanpet with Chennai International Airport extending for with being underground and the second corridor would connect St.Thomas Mount with Chennai Central extending for with being underground. In December 2007, the Chennai Metro Rail Limited (CMRL) was established as a joint venture between the union and state governments to execute the project. The Planning commission gave an in-principle approval for the project in April 2008 with the final approval by the Union Council of Ministers in January 2009. The estimated base cost of the first phase was of which 59% was loaned by Japan International Cooperation Agency (JICA). The Government of India contributed 15% of the cost and the Government of Tamil Nadu financed the remaining 21% of the project.
+ Major contracts awarded during Phase 1 construction Year Scope of contract work Contractor Contract Value Notes February 2009 Construction of elevated 4.5 km viaduct between Koyambedu and Ashok Nagar along Inner Ring Road Soma Enterprise March 2009 Technical consultancy services for Phase 1 project Egis-led consortium of five companies US$30 million August 2010 Supply of rolling stock metro trainsets Alstom US$243 million January 2011 Design and construction of tracks and Koyambedu depot Larsen & Toubro – Alstom joint venture January 2011 Construction of 9 underground stations and tunnels in Blue and Green lines of Phase 1 Afcons–Transtonnelstroy January 2011 Construction of 3 underground stations and tunnels in Green Line of Phase 1 Larsen & Toubro - SUCG JV February 2011 Construction of 7 underground stations in Blue Line of Phase 1 Gammon India and Mosmetrostroy June 2011 Construction of ten elevated stations Consolidated Construction Consortium June 2011 Supply and installation of lifts and escalators Johnson Lifts – SJEC Corporation joint venture June 2011 Power supply systems and overhead electrification Siemens June 2011 Automatic fare collection system Nippon Signal June 2011 Tunnel ventilation systems Emirates Trading Agency June 2011 Air conditioning systems Voltas
In August 2012, a construction worker was killed and six others were seriously injured after a crane failed and crashed at an under construction site near Pachaiyappa's College and on 10 January 2013, a 22-year-old construction worker was killed and three others were injured at a construction site between Alandur and St. Thomas Mount. On 6 November 2013, a test run was conducted along a stretch of track. The project faced several delays and missed deadlines due to problems with land acquisition and cancellation of construction contracts. On 11 January 2014, a crane toppled over, killing a 20-year-old construction worker and seriously injuring another at Saidapet.
On 14 February 2014, the maiden trial run was conducted between Koyambedu and Ashok Nagar stations. The metro received the statutory speed certification clearance from the Research Design and Standards Organisation in August that year. In January 2015, a report was submitted to the Commissioner of Metro Rail Safety (CMRS) for mandatory safety approvals. After inspecting the infrastructure, the CMRS submitted the report to the Railway Board in April 2015.
Operations on the Green Line between the Alandur and Koyambedu stations commenced on 29 June 2015. The Blue Line segment from the Airport and Little Mount stations commenced operations on 21 September 2016. The first underground section between Thirumangalam to Nehru Park on the Green Line opened on 14 May 2017, and the extension to Chennai central was completed on 25 May 2018 along with the section from the Saidapet and AG-DMS stations on the blue line. On 10 February 2019, the underground stretch from AG-DMS to Washermanpet of Blue Line was opened, marking the completion of the first phase of the metro.
+Chennai Metro - Phase I timelineLine NameTerminalsStationsOpenedGreen LineKoyambeduAlandur729 June 2015AlandurSt. Thomas Mount114 October 2016KoyambeduNehru Park715 May 2017Nehru ParkCentral225 May 2018Blue LineChennai AirportLittle Mount621 September 2016Little MountAG–DMS425 May 2018AG–DMSWashermanpet710 February 2019
Phase I Extension In 2014, a northern extension of the Blue Line was announced by the Government of Tamil Nadu. The extension would run from Washermanpet to Wimco Nagar and consist of nine stations. Construction started in July 2016 with the first trial runs conducted in December 2020. The line opened for passenger traffic on 14 February 2021, increasing the length of the operational metro system to . The expansion costed of which 57% was loaned by JICA. In 2021, the CMRL proposed a further extension of the blue line to connect the airport with Kilambakkam at an estimated cost of , which is clubbed with Phase III in 2026.
+Chennai Metro - Phase I Extension LineTerminals Length Stations Opened/statusBlue LineWashermanpetWimco Nagar814 February 2021Wimco NagarWimco Nagar Depot113 March 2022
Phase II
In July 2016, the Government of Tamil Nadu announced that the second phase would have three lines spanning with 104 stations. Two corridors would extend from connecting with Siruseri SIPCOT and respectively with the third corridor connecting Koyambedu with on the Marina beach. In July 2017, the state government announced an extension of Phase II, involving a section from Lighthouse up to with an intersection with the Madhavaram–Sholinganallur line at Alwarthirunagar. The second phase would span with 128 stations. The stations for the second phase were designed to be smaller than the stations of the first phase to reduce the cost and time of construction. In 2019, the Madras High Court questioned the state government on the construction method of the tunnels and its impact on the water bodies. The second phase was estimated to cost of which was loaned by JICA.
On 20 November 2020, foundation stone for the second phase was laid and construction commenced. On 14 February 2021, Prime Minister of India announced that the government has set aside for the construction of the second phase and its further extension. In May 2023, the CMRL announced minor changes to the lines' alignment and that nine stations would be scrapped in the revised plan. Hence, the total length of the second phase was reduced to .
+ Major contracts awarded during Phase 2 construction Year Scope of contract work Contractor Contract Value Notes May 2021 Civil construction of various sections of Phase 2 Tata Group, Larsen & Toubro (L&T), HCC-KEC November 2022 Rolling stock supply of 78 train sets including 36 driver-less trains Alstom December 2022 Installation of tracks KEC–Vijay Nirman Company JV December 2022 Installation of signalling systems Hitachi January 2023 Construction of 12 underground stations in Purple Line Rail Vikas Nigam Limited (RVNL) January 2023 Installation of electric traction systems Linxon May 2023 Installation of overhead equipment and control and monitoring systems Larsen & Toubro (L&T) October 2023 Construction of 5 underground stations of Red Line Tata Projects December 2023 Installation of platform screen doors at 36 elevated stations ST Engineering December 2023 Installation of automated fare collection systems Shellinfo March 2024 Additional supply of 96 train sets Alstom
, about of the second phase had been completed. In March 2025, the first trial run on the Phase II network was conducted on a stretch between Poonamallee and Mullaithottam on the proposed Yellow Line. In April 2025, trial runs began on a stretch between Poonamallee and stations on the same line. The RDSO conducted inspection on the same stretch in August 2025, and the Railway Board provided approval for the operation of signals on the line in December 2025. Following the conclusion of safety checks by the CMRS in February 2026, the operations on to stretch on the Yellow Line, with no intermediate stoppages between and Vadapalani, is expected to begin in October 2026.
+Chennai Metro - Phase IILineTerminalsLengthStationsStatusYellow Line11Opens October 11, 20266Under construction10Purple LineSiruseri SIPCOT II48Red Line45118
Proposed Phase III In 2022, the state government proposed an extension plan spanning for the three under construction lines of the second phase. The proposal involved extension of Purple Line from Siruseri SIPCOT to Kilambakkam, Yellow Line from Poonamallee to Parandur and Red Line from Koyambedu to Avadi. The proposed extension of second phase lines from Siruseri to Kilambakkam, Poonamallee to Parandur, and Koyambedu to Avadi were projected to cost , , and respectively. Between late 2023 and early 2024, feasibility reports submitted by the CMRL suggested dropping the proposed extension of the purple line due to economic viability and going ahead with the planned extensions of the other two lines, spanning . In May 2024, the state government proposed a new extension from Madhavaram to Ennore, which was later changed as Assisi Nagar to Wimco Nagar extension in 2026.