Chennai Metro Rail (CMRL) has successfully completed the construction of a tunnel between Ayanavaram and Perambur as part of its Rs 63,246-crore Phase-II expansion project, marking a significant milestone after over 18 months of work.

The tunnel boring machine (TBM) 'Kalvarayan' bored an 867-mtrs. tunnel, achieving a breakthrough at Perambur on 13 May, 2025. This marks the 11th tunnel completed so far in the ongoing project. The Phase II project spans 118.9 km, with three corridors -  Madhavaram–SIPCOT, Light House-Poonamallee, and Madhavaram–Sholinganallur.

Of the total length, 42.6 km will be underground, with 48 planned stations. The Ayanavaram–Perambur section forms part of the Madhavaram–SIPCOT corridor. According to officials of CMRL, this tunnel presented complex challenges, and a key hurdle was completing the diaphragm wall at the Perambur station, necessary for TBM breakthrough.

Although more than 95 percent of the tunnel was bored, the TBM had to wait due to delays in station construction, attributed to the earlier cancellation of station construction tenders.