Chennai Metro

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 54.1 km and has 41 underground and elevated stations. The system runs on standard gauge and is powered by 25 kV 50 Hz AC 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 118.9 km 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

Proposed Phase III

In 2022, the state government proposed an extension plan spanning 93 km 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 ₹54.58 billion (US$570 million), ₹107.12 billion (US$1.1 billion), and ₹67.36 billion (US$700 million) 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 59.7 km. In May 2024, the state government proposed a new 16 km extension from Madhavaram to Ennore, which was later changed as Assisi Nagar to Wimco Nagar extension in 2026.

In May 2024, the Government of Tamil Nadu approved both the extensions of the Red Line from Koyambedu to Pattabiram and Yellow Line from Poonamallee to Parandur at an estimated cost of ₹99.28 billion (US$1.0 billion) and ₹159.06 billion (US$1.7 billion) respectively, forwarding to Government of India for final approval. In July 2026, Chennai Metro planned to club Airport - Kilambakkam extension of Phase-I as well as above planned extensions with proposed Phase III network, with few more stretches planned to link northern suburbs of city based on feasibility reports. Koyambedu metro station is set for upgrade with Phase III connectivity (Koyambedu - Pattabiram) with Phase I and Phase II stations of Green Line and Red Line respectively. CMRL also plans extending Airport to Kilambakkam extension further south, till Chengalpattu.

Integration of MRTS

In 2017, the state government proposed to integrate the Chennai Mass Rapid Transit System (MRTS) into the Chennai Metro. In July 2018, PwC said that the merger would cost around ₹30 billion (US$310 million) to convert the rolling stock and install other facilities for the merger. On 11 May 2022, Southern Railway of the Indian Railways granted an in-principle approval for the integration of the MRTS into the metro. As per the plan, the railway would handover the MRTS to the CMRL once the expansion of the MRTS is completed. However, the extended second phase of the MRTS project, connecting Velachery with St. Thomas Mount experienced delays, and was completed in March 2026. Once the takeover is completed, CMRL will upgrade the MRTS system including tracks, security, ticketing system and rolling stock.

Metrolite

In 2020, a light rail was proposed to connect Tambaram railway station of the existing suburban rail network with Velachery on the MRTS, as part of plans to link the different urban transit lines in the city. Feasibility studies for the project was commissioned in February 2023 by the Chennai Unified Metropolitan Transport Authority (CUMTA). In March 2024, a study was commissioned to re-assess the feasibility of establishing a new corridor connecting Tambaram with Velachery with an extension to connect with existing Guindy metro station. In 2025, the government decided to develop the stretch as a regular metro corridor.

Others

The third phase of the Chennai Metro is under planning as a part of the Chennai Comprehensive Mobility Plan, with upgrades to existing Phase-I stations and procurement of 28 new six-coach metro trains. The CMRL is also involved in the feasibility studies for the development of metro rail transport in the cities of Coimbatore, Madurai and Tiruchirapalli.

CMRL developed the Kathipara Urban Square as a multi-modal transport hub with parking and recreational areas. In 2023, the CMRL proposed the development of Central Square around its headquarters with commercial complexes and multi-storied buildings. In April 2025, CMRL announced that it has identified public spaces in Adyar and Velachery which can be transformed into public spaces similar to Kathipara Urban Square.

Infrastructure

Network and lines

Chennai Metro runs on 1,435 mm (4 ft 8+1⁄2 in) standard gauge and the lines are double-tracked. The trains can operate at a maximum speed of 120 km/h, and the average operational speed is 85 km/h.

As of December 2025, the operational network consists of two colour-coded lines covering a length of 54.1 km.

Rolling stock

Alstom supplied the rolling stock for the first phase of the Chennai Metro. For the first phase, it supplied 42 train-sets composed of four coaches. The first nine train sets were imported from Brazil and the rest were manufactured at Alstom's facility at Sri City near Chennai. The trains are air-conditioned with electrically operated automated sliding doors. The trains usually have a first class compartment and a dedicated section reserved for women.

The trains operate on 25 kV AC electric traction. The trains are connected to the grid via overhead lines and are equipped with regenerative braking with a capacity to recover 30–35% of the energy during braking. The electricity is supplied by the Tamil Nadu Electricity Board, and the metro system consumed an average of 70 MW of power daily in 2014. Chennai Metro also uses solar power with an installed capacity of 6.4 MWp, which contributed to about 12-15% of the energy requirement of the metro in 2023.

For the second phase, Alstom was awarded a ₹9.47 billion (US$98 million) contract to supply 26 trainsets made of three coaches each to be deployed on the Yellow Line. In November 2024, CMRL awarded a ₹36.58 billion (US$380 million) contract to BEML for the supply of 70 trainsets, made of three coaches each, to be deployed on Red and Purple lines. In June 2025, CMRL placed an additional order of 32 driverless trainsets with Alstom.

Stations

A total of 40 stations, 22 of which are underground, are operational on the two lines of the first phase. In the underground sections, a walkway runs along the length of the corridor with cross passages every 250 m for the maintenance and emergency evacuation. The underground stations have an average width of 200 m and are located at an average depth of 6.1 m from the ground level. The average length of the stations in Phase 1 extension is about 180 m.

The elevated stations have three levels with the concourse level at a minimum height of 5.5 m above the ground level and platform level above the concourse while the underground stations have two levels and are equipped with platform screen doors. The stations are air-conditioned and are equipped to be disabled and elderly friendly, with automated fare collection, public announcement system, electronic display boards, escalators and lifts. Paid parking facilities are available for two wheelers in most stations and four wheelers in select stations.

Depots

Chennai Metro maintains a major depot at Koyambedu which houses maintenance workshops, stabling lines, test tracks and a washing plant for the trains. In 2022, an elevated depot at Wimco Nagar commenced operations with the same facilities. Three new depots at Madhavaram, Poonamallee, and Semmencherry, are planned as a part of the second phase, of which Madhavaram depot is planned to be the largest. The Poonamallee depot was first in Phase II to commence operations with trial runs being conducted since 2024. In 2025, a sixth depot was planned at Pattabiram as a part of the Phase-III expansion of the Chennai Metro.

Operations

As of 2022, the metro operates trains from 5:00 am to 11:00 pm. The blue line has an average frequency of every 6 minutes during peak hours and every 12 minutes during off-peak hours. On the green line, the average frequency is 12 minutes during peak hours and 18 minutes during off-peak hours. The main operational control center (OCC) is located in Koyambedu where the movement of trains and real-time CCTV footage obtained is monitored. In 2022-23, the average daily ridership was 0.25 million.

Fare and ticketing

The minimum fare is ₹10 and the maximum fare is ₹50.

There are six types of tickets issued by CMRL for travel in Chennai Metro.

Single journey tokens, which need to be purchased each time for every journey at the ticket counter or in ticket vending machines available at all stations.

Stored value cards (SVC) are pre-paid, rechargeable, travel cards that can be purchased at any ticket counter against a refundable deposit, can be recharged up to at any ticket counter or in automated ticket vending machines at stations and offers discounted fares. In April 2023, National Common Mobility Card replaced the Stored value cards.

Trip cards are for applicable for travel between the same two stations and are available in varied combinations and validity with discounted fares.

Tourist cards provide the cardholders unlimited rides on the Chennai Metro system for one day.

QR Tickets for single and return journey tickets can be bought through the CMRL mobile app with QR code ticket scanners at stations.

National Common Mobility Card, also branded as Singara Chennai card, a stored-value cum debit card launched in 2023 in association with State Bank of India which can be used to access all major other metro and select bus transport systems in India.

Incidents

On 17 June 2015, a 30-year-old man was killed and another motorcyclist injured when an iron rod fell on them at a metro construction site near Officers Training Academy at St. Thomas Mount.

On 27 September 2022, a crane used for transporting iron rods crashed near Ramapuram, causing the rods to fall on a Metropolitan Transport Corporation bus and injuring the bus driver, conductor, and crane operator.

On the night of 13 June 2025, two girders of the under-construction Poonamallee–Porur Metro section collapsed in Manapakkam, killing a 43-year-old man. CMRL imposed a fine of ₹10 million (US$100,000) on the contractor Larsen & Toubro for the incident.