CHENNAI: CMRL has begun simultaneous trial runs on both up and down lines of Corridor 4’s 9.5km viaduct from Porur junction to Poonamallee bypass as part of its Rs 63,000 crore Phase 2 expansion project. The dual-line trial, which commenced on Friday, signals progress toward the targeted December 2025 launch.
Six driverless trains, manufactured by Alstom, will operate on this stretch under unattended train operations, with manual supervision for the first five to six months. “We are focused on a gradual transition to ensure stability and safety,” said MA Siddique, CMRL MD.
The 10-station elevated stretch had earlier seen phased testing on the 3km upline between Mullaithottam and Poonamallee and a 9.1km segment from Porur to Poonamallee. Friday’s downline test marked the first full-directional run, with Poonamallee depot serving as the operations hub during commissioning.
Civil works, track laying and overhead electrification have been completed. Current trial speeds are capped at 25 kmph, with expectations to reach 60-70 kmph within a month. Signalling installation will begin in July. The system will be more advanced than the Phase I setup, which used Grade of automation-2 technology. Delhi Metro Rail Corporation, supporting implementation, has started hiring personnel for signalling software testing.
Alstom has delivered six three-car train sets so far, with more en route. Siddique noted that earlier challenges in building the double-decker viaduct near Kattupakkam, caused by labour shortages, have been resolved.
Other Phase II stretches -- including Porur to Kodambakkam Power House, Alapakkam to Chennai Trade Centre, and the Koyambedu double-decker corridor -- are expected to be completed by mid-2026. CMRL is also piloting predictive maintenance using AI in Phase I. The system, powered by real-time sensor data, aims to reduce unplanned disruptions and improve network reliability.
In a related development, the auxiliary substation at Poonamallee bypass was energised Friday with a 33kV supply from Poonamallee receiving substation. Siddique inaugurated the facility alongside directors T Archunan, Manoj Goyal, S Krishnamoorthy, and AR Rajendran.
Meanwhile, the Airport-Kilambakkam metro extension faces delays due to design changes. MoHUA has asked TN to update its Comprehensive Mobility Plan and resubmit a revised DPR.