Chennai Metro Rail (CMRL) will induct 28 new six-car trains by 2028 on its 54-km Phase I network to reduce congestion and improve frequency during peak hours.

This move will bring down train frequency to three minutes on Corridor One (Airport–Wimco Nagar) and four to five minutes on Corridor Two (Chennai Central–St. Thomas Mount), compared to the current six to 12 minute intervals. Many trains now run as short-loop services instead of covering the entire stretch.

The expansion comes in response to growing ridership and anticipated demand from Phase II, expected to be operational by 2026–27, along with the Corridor One extension to Kilambakkam. According to CMRL Director (Projects) T. Archunan, the combined fleet will grow to 80 trains, including the current 52 four-car trains. To support six-car operations, 21 underground stations will undergo infrastructure upgrades. 19 of these will receive electrical integration for platform screen doors (PSDs), while others will see full platform extensions and new PSDs.

Elevated stations like Guindy, Alandur, Airport, and CMBT will also be retrofitted. Depots at Koyambedu and Wimco Nagar are being upgraded with new stabling lines, washing plants, and inspection bays to accommodate the fleet expansion.