An August 18 state order authorizes Chennai Metro Rail Limited (CMRL) to begin preliminary work on the 21.76-km Koyambedu–Avadi–Pattabiram corridor, which will run via Avadi along the Outer Ring Road. The fully elevated line is planned to have 19 stations, including Padi Pudhu Nagar, Golden Flat Junction, Ambattur Estate, Ambattur Station, Ambattur OT, Thirumullaivoyal, Avadi Railway Station, Pattabiram and Outer Ring Road.

The project is estimated to cost ₹9,928.33 crore. Tamil Nadu will provide CMRL a ₹2,442 crore subordinate loan for initial activities; ₹188 crore is estimated for surveys, tree removal and replanting, traffic management and utility shifting, with a major share of funding allocated to land acquisition. A detailed proposal was submitted in May, but the project still needs Union government clearance and a Comprehensive Mobility Plan (CMP) for further assessment. Avadi residents have urged the state to expedite the CMP submission.

Tamil Nadu has granted administrative sanction for preparatory work on the 21.76-km Koyambedu–Avadi–Pattabiram Chennai Metro corridor. The fully elevated line is planned to have 19 stations.

Chennai Metro Rail Limited (CMRL) can begin land acquisition, utility shifting and surveys. The State submitted the detailed project report to the Centre in May; final approval is pending, and CMRL must submit a Comprehensive Mobility Plan to the Ministry of Housing and Urban Affairs for review.

The corridor is estimated to cost ₹9,928.33 crore. The State allocated ₹2,442 crore to CMRL as subordinate debt for preparatory work, including about ₹188 crore for topographic surveys, geotechnical investigations, tree replantation and traffic management. Much of the funding will go towards land acquisition and structure costs.

Tamil Nadu has sanctioned ₹13.5 crore to complete the unfinished second arm of the Pattabiram road overbridge (ROB), with State Highways officials expecting work to finish in two to three months. About 100 metres of work remains. The other arm, inaugurated on September 25, 2024, is 5.5 metres wide and carries two-way traffic across three lanes, separated by a median.

The proposed 780-metre-long, 11-metre-wide ROB was designed as a six-lane carriageway to replace the level crossing between Pattabiram and Pattabiram Military Siding stations. The project received ₹78.35 crore in 2022, which has been utilised. Approved in 2011, construction began in 2018 and faced delays related to land acquisition, the Covid-19 lockdown, cost escalation and design issues. The bridge serves the Chennai-Tirupati NH 205 and Pattabiram-Thiruninravur stretch; motorists report narrow passage and traffic risks. A planned roundabout near Pattabiram Police Station has not been built.

Chennai Metro Rail Limited (CMRL) has proposed a ₹9,744 crore metro extension from Koyambedu to Pattabiram. The 21.76-km line would have 19 elevated stations and aims to improve connectivity.

• The Detailed Project Report (DPR) for the 16.1-km Koyambedu–Avadi extension was nearing completion and expected by the end of January 2025. Chennai Metro Rail Corporation submitted a feasibility report to RITES in July 2024.
• A feasibility study for extending the route from Avadi to Pattabiram is underway. Pattabiram’s projected peak-direction traffic is about 12,000 passengers per hour. If the study is successful, its report will be submitted to the government within a month.
• Extending the route to Pattabiram would increase its length to almost 20 km. The estimated project cost is ₹6,500 crore, with about 15 elevated stations and a depot planned in Avadi or on vacant land near the Outer Ring Road in Pattabhiram.
• Proposed station locations include Koyambedu, Padi Puthu Nagar, Vavin, Ambattur Estate Bus Stand, Ambattur Railway Station, Thirumullaivayal, Avadi Railway Station, and Thirumangalam or Mogappair.
• Chennai’s two metro lines cover 54 km and carry over 3.20 lakh passengers daily. More than 35.53 crore passengers have used the service in nine years; 10.52 crore travelled in 2024.