While the suburban railway has been operational in Chennai 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 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 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.

[7] The system was envisaged as a 59.38 km (36.90 mi) loop line connecting Chennai Beach and Tiruvottiyur.

[8] Since the planned railway line would pass through congested parts of the city, an elevated rail system was selected, to avoid land acquisition problems.

[10][20] The initial planned alignment was altered subsequently and necessitated the demolition of over 70 residential units, which led to protests by the locals.

[23] 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.

[40] 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.

[42] In July 2018, PwC said that the merger would be expensive, costing around ₹30 billion (US$350 million) to replace the train-sets and establish other facilities.

[7][10][40] 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.

[7][10][46] 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.

[10][40] The route taken by the MRTS line has resulted in the pillars of the elevated section of the railway encroaching the Buckingham Canal.

[73] The MRTS passes along the Old Mahabalipuram Road (OMR), which also forms part of the information technology corridor where many companies are located.

[78] There are large stations on the existing MRTS line designed to accommodate six and nine-car train rakes with attached parking lots.

[82][83][84][85] MRTS has been criticised by the public for poor maintenance of the stations, lack of inter-modal transport facilities and security issues.

[86][87] The director of Chennai Metro called for the various government agencies to work together to improve the connectivity to the stations.

[89][90][91] A 2006 report by the Comptroller and Auditor General of India cited delays in installation of station amenities such as escalators.

[93] In 2013, to improve the security for the passengers using the network, Indian Railways declared that the MRTS stations would have a single designated entry and exit point as it was difficult for the existing RPF personnel to monitor multiple gates at the same time.

Plans to modernise infrastructure include improved facilities at stations and single integrated ticketing system among others.

[96] The operational route length between Chennai Beach and Velachery is 19.34 km (12.02 mi) with a journey time of more than 45 minutes one way.

[117] In 2023, Chennai Unified Metropolitan Transport Authority (CUMTA) introduced new plans to improve last-mile connectivity to the stations.

[69][119] Special trains are run when cricket matches are hosted at the M. A. Chidambaram Stadium in Chepauk,[73][120][121] during Kaanum Pongal festival at Marina Beach,[122] and during bus strikes.

[124][125] As per a survey conducted in 2012, the public called for special focus on pedestrian facilities that would provide access to MRTS stations from nearby roads and bus stops, as well as identifying new feeder routes for the network.

This would enable commuters to access the railway grid of the different operational rail systems and facilitate improved connectivity from the stations on the MRTS network.

[127] The proposed extension up to St. Thomas Mount is expected to increase patronage from people working in the IT establishments, residences and other offices located close to the MRTS network.

[118][130] A major contributor to the losses is the revenue deficit due to subsidised cheaper fares offered by the Southern Railway, which runs the service.