Yellow Line (Chennai Metro)

Phase II

The construction of the first phase of Chennai Metro started in June 2009.^[2] Commercial operations started on the green line in June 2015.^[3][4][5] On 10 February 2019, the extension of blue line was opened, completing the first phase of the metro.^[6]

In July 2016, Government of Tamil Nadu announced that the second phase would have three lines totaling 104 km (65 mi) in length with 104 stations.^[7][8] Two corridors would extend from Madhavaram Milk Colony connecting with Siruseri and Sholinganallur respectively with the third corridor connecting Koyambedu with Lighthouse. In July 2017, the state government announced an extension in Phase II, involving an extension of line four from Lighthouse up to Poonamallee with an intersection with the Madhavaram–Sholinganallur line at Alwarthirunagar. The line will extend to 26.1 km (16.2 mi) with 16 km (9.9 mi) elevated and 10.1 km (6.3 mi) underground. It will consist of 30 stations including 12 undergrounds stations.^[9][10] The stations for the second phase were designed to be smaller than the existing stations operational in the first phase.^[11]

On 20 November 2020, foundation stone for the second phase was laid and construction commenced.^[12] In November 2022, Alstom was awarded the contract to supply metro coaches for the phase II expansion.^[13] In May 2023, CMRL announced a revised plan for the second phase. As per the plan, the line will extend for 26.1 km (16.2 mi) with 27 stations.^[14][15]

The second phase is estimated to cost ₹632.46 billion (US$6.6 billion) of which initially ₹47.1 billion (US$490 million) was loaned by Japan International Cooperation Agency.^[9][16][17] On 14 February 2021, the Prime Minister of India announced that the government has set aside ₹630 billion (US$6.5 billion) for the construction of phase II and further extension.^[18]

In January 2025, Chennai Metro announced that the operations on Poonamallee Bypass to Vadapalani stretch will start in February 2026, with no intermediate stoppages at stations from Alapakkam to Saligramam.^[21] The opening has since been postponed due to Tamil Nadu Assembly election and is now expected in the second or third week of July 2026, during Prime Minister Narendra Modi's visit.^[20]

Phase II extension

In 2022, the state government proposed an extension plan for the fourth line from Poonamalee to Parandur, covering an approximate 52.9 km (32.9 mi).^[22] Detailed Project Report (DPR) of the line was prepared and submitted to Government of Tamil Nadu which approved the line in June 2025. This extension would be implemented in 2 phases, from Poonamallee Bypass to Sunguvarchatram in first phase and then to Parandur in second phase. The DPR is currently forwarded to Government of India for final approval.^[23] Another extension of the corridor eastward from Lighthouse to High Court is also being planned.^[24]