On 7 April 2012, the Madras High Court dismissed a petition filed by the Indian National Trust for Art and Cultural Heritage challenging the demolition of a building on Anna Salai. In July 2012, the first tunnel boring machine was launched and by October 2012, eleven machines were commissioned to bore tunnels along the underground stretch by three consortiums, namely Afcons-Transtonnelstroy, L&T and SUCG, Gammon India and Mosmetrostroy involved in the construction. On 6 November 2013, the test run along a stretch of track was conducted. On 14 February 2014, the maiden trial run for the metro was conducted between the Koyambedu and Ashok Nagar stations. In August 2014, the metro received the statutory speed certification clearance from the Research Design and Standards Organisation. In January 2015, a report was submitted to the Commissioner of Metro Rail Safety for approval. In April 2015, the Commissioner of Metro Rail Safety inspected the rolling stock and submitted a report to the Railway Board. On 29 June 2015, commercial operations started between Alandur and Koyambedu stations. Almost a year later, on 21 September 2016, commercial operations commenced between Chennai International Airport metro station and Little Mount. Commercial operations commenced in the first underground line between Thirumangalam metro station to Nehru Park metro station on 14 May 2017. The underground stretches – Nehru Park metro station to Chennai Central metro station and Saidapet metro station to AG-DMS metro station were opened a year later on 25 May 2018. On 10 February 2019, the underground stretch from AG-DMS to Washermanpet of blue line was opened, completing phase 1 of the metro.