In what could be an unconventional alignment, Chennai Metro Rail Limited’s (CMRL) corridor 5 line will cut through the Adambakkam MRTS station’s roof.

A part of the phase 2 network, corridor 5 runs from Madhavaram to Sholinganallur via Retteri, Kolathur, Villivakkam, Anna Nagar West, Thirumangalam, Koyambedu, Virugambakkam, Mugalivakkam, Ramapuram, Manapakkam, Chennai Trade Centre, Adambakkam, Ullagaram, Madipakkam, Kovilambakkam, Medavakkam, and Perumbakkam.

The alignment runs over the cloverleaf flyover and phase 1 corridor at Alandur, and passes through Railway Station Road and St. Thomas Mount. Then, it travels parallel to the MRTS corridor at Adambakkam and cuts through the Adambakkam MRTS station roof, before proceeding towards Vanuvampet.

Once the corridor becomes operational, Metro trains will run perpendicularly above the MRTS track at Adambakkam. To build this, a small portion of the Adambakkam MRTS station roof was dismantled. Then, after removing the vertical columns and the stations’ parapet wall, temporary beams and steel I-girders were installed block by block. Subsequently, the deck slabs (where the CMRL tracks will be laid) were built, and the roof was rebuilt.

T. Archunan, Director (Projects), CMRL, said the alignment cuts through that of the MRTS network. “But we decided to retain this design. Else, we would have to disturb the residences in the locality.” Also, building the corridor over the MRTS station meant the viaduct and the subsequent phase 2 station at Vanuvampet would be taller, resulting in high construction costs.

“The CMRL viaduct is built nearly 20 m above the ground. At first, we got the approval from the Commissioner of Railway Safety, as the Metro Rail train will run right above the overhead line of the MRTS train. We began the work by dismantling the roof structures and overhead equipment line at the Adambakkam MRTS station,” he said.

“The construction began last year and went on for three months. We had to deploy steel girders because it is not possible to use concrete and build over an existing railway line at this location. The length of the steel I-girder curve portion over the MRTS track is 56 metres. CMRL is the first Indian metro to use steel composite girders in curves,” he said. It was done before the MRTS extension line from St. Thomas Mount to Velachery via Adambakkam was commissioned, he added.

Unconventional design

Published - August 08, 2026 10:40 pm IST