Yellow Line (Chennai Metro)
The Yellow Line or Line 4 is one of the under construction lines of Chennai Metro Phase-II stretching from to. The line will consist of 27 stations, out of which nine will be underground and 18 will be at grade or elevated. The colour code of the corridor was changed from Orange to Yellow, as per latest CMRL's latest Phase-II map.
Planning and construction
Phase II
The construction of the first phase of Chennai Metro started in June 2009. Commercial operations started on the green line in June 2015. On 10 February 2019, the extension of blue line was opened, completing the first phase of the metro.In July 2016, Government of Tamil Nadu announced that the second phase would have three lines totaling in length with 104 stations. Two corridors would extend from connecting with Siruseri and 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 with elevated and underground. It will consist of 30 stations including 12 undergrounds stations. The stations for the second phase were designed to be smaller than the existing stations operational in the first phase.
On 20 November 2020, foundation stone for the second phase was laid and construction commenced. In November 2022, Alstom was awarded the contract to supply metro coaches for the phase II expansion. In May 2023, CMRL announced a revised plan for the second phase revising the station count on the fourth line to 27. As per the final plan, the fourth line will extend for.
The second phase is estimated to cost of which initially was loaned by JICA. On 14 February 2021, Prime Minister of India announced that the government has set aside for the construction of phase II and further extension.
In January 2025, Chennai Metro announced that the operations on to stretch will start in February 2026, with no intermediate stoppages at stations from Alapakkam to Saligramam.