Chennai Metro Phase II Corridor 4 — the Yellow Line — completed 100 days of revenue operations on the Poonamallee Bypass ↔ Vadapalani stretch. Ridership has been growing 8–11% week-on-week; CMRL reports 2.1 lakh daily passenger boardings as of mid-May.

The line was opened to passengers in March 2026 after the Tunnel Boring Machine "Peacock" completed its first underground breakthrough in July 2025. The full corridor — extending to the Lighthouse end of Marina — remains under construction with a 2027 commissioning target.

Eight stations are operational: Poonamallee Bypass, Karambakkam, Porur Junction, Mugalivakkam, Manapakkam, Alandur Metro, Vadapalani Bus Terminus, and Vadapalani. Fares range from ₹10–60 with end-to-end at ₹50.