Chennai Metro Rail’s tunnel boring machine ‘Flamingo’ to bore near Thirumayilai MRTS station after nod from Commissioner of Railway Safety

The launch of a tunnel boring machine (TBM) at Light House station, in Chennai. File

| Photo Credit: M. Srinath

Chennai Metro Rail’s tunnel boring machine (TBM) Flamingo, which has been boring from Light House since 2023, can reach Thirumayilai only after receiving approval from the Commissioner of Railway Safety (CRS).Chennai Metro Rail’s phase II project with three corridors — Madhavaram to SIPCOT (corridor 3), Light House to Poonamallee (corridor 4), and Madhavaram to Sholinganallur (corridor 5) — intersects with suburban railway stations, MRTS stations, and Chennai Metro Rail’s phase I corridor at multiple locations. Thirumayilai is one such location, wherein the phase II station and the MRTS station are built close together and will be integrated in the future.According to officials from Chennai Metro Rail Limited (CMRL), CRS approval is required because Flamingo will come in close proximity to the pile structure of the Thirumayilai MRTS station. As a result, before the TBM can make a breakthrough on the eastern side of the diaphragm wall or the station box of the Thirumayilai Metro Rail station, CMRL must obtain approval from the CRS to ensure safety.“The TBM Flamingo has to cover a distance of 1.96 km to drill a tunnel between Light House and Thirumayilai. At present, Flamingo is 94 metres away from the Thirumayilai Metro Rail station and awaits a breakthrough. It will pass within 10 metres of the MRTS station pile before reaching the breakthrough point. Hence, approval is mandatory. We are carrying out the work carefully, and there will not be any issues,” an official said.Before CMRL sends an application seeking approval, IIT Madras will carry out a simulation to check whether there will be any soil settlement and tilt when the machine comes close to the MRTS station pile. “If they find that the settlement is well within the permissible limit, we can go ahead with the tunnel breakthrough. They will check how the influence zone of the soil will react if this work is carried out. They will also recommend the permissible speed at which the TBM can drill through this stretch,” he noted.CMRL will communicate with IIT Madras shortly, and it will take them about a month to complete the simulation. Following this, CMRL will send documents to the CRS requesting clearance. Initially, when the TBM commenced work, CMRL said it would arrive at Thirumayilai in a year’s time, but there have been delays due to the difficulties involved in tunnelling along this stretch. A few months ago, CMRL said the machine would make a breakthrough in September, but that has now been pushed to November. Published - September 24, 2025 05:23 pm IST