The Tamil Nadu government has granted administrative sanction to Chennai Metro Rail (CMRL) for preparatory work on the 21.76-km Koyambedu–Avadi–Pattabiram corridor.

This allows CMRL to begin land acquisition, utility shifting, surveys, traffic management, and tree replantation, even as it awaits final clearance from the Union government. The state had earlier submitted the detailed project report to the Centre in May but must still provide a Comprehensive Mobility Plan (CMP) for approval. According to the order dated August 18, the corridor will be constructed along the Outer Ring Road with 19 stations, including Ambattur Estate, Avadi Railway Station, and Pattabiram.

While the total project cost is estimated at Rs 9,928.33 crore, the state has allocated Rs 2,442 crore as subordinate debt for preparatory works, of which Rs 188 crore will cover surveys, investigations, and tree management. A large portion will go toward land acquisition and structure costs. Residents have urged quick Centre approval, citing heavy commuter demand.