Flamingo and Eagle, the two TBMs, started their tunnelling journey nearly two years back from the Light House station and are scheduled to reach the Thirumayilai Metro Rail’s phase II station shortly. File
| Photo Credit: The Hindu
Two tunnel boring machines (TBMs) deployed for Chennai Metro Rail’s phase II project to build an underground network between Light House and Thirumayilai have been temporarily stopped now.
Flamingo and Eagle, the two TBMs, started their tunnelling journey nearly two years back from the Light House station and are scheduled to reach the Thirumayilai Metro Rail’s phase II station shortly. After passing through nearly 160 buildings, which include an old church, school and an embassy, Flamingo TBM and the Eagle TBM are currently taking a break from the tunnelling work.
According to officials in the Chennai Metro Rail project, both the TBMs are now going through a process called cutter head intervention. “Cutter head, an important unit in a TBM endures a lot of wear and tear while boring the earth. Hence, we are now carrying out the cutter head intervention process wherein the tools of the cutter head are changed. This will take some time and then the machines will resume their drilling work,” an official said.
Both Flamingo and Eagle have to drill a total of 1.9 km to build twin tunnels linking Light House with Thirumayilai. This 1.9 km stretch currently getting shaped is an underground section in corridor 4 of the phase II project which connects Light House with Poonamallee via Thirumayilai and T-Nagar.
“We encountered difficult soil strata along this Light House-Thirumayilai stretch. Initially, closer to the Marina Beach, there was sandy soil, and then subsequently, there was some clayey soil and rock at some points. But in many locations, there was abrasive sand which made tunnelling pretty difficult. We had to change the parts of the cutter head as many as 25 times,” he added.
This 1.9 km tunnelling stretch covers three underground stations — Light House, Kutchery Road and Thirumayilai. While the Flamingo TBM commenced the drilling work first in September 2023, it will be the second TBM Eagle which will complete the tunnelling first, make a breakthrough first, and be taken out in the first week of October.
This is because the Kutchery Road underground station has been planned as a stacked station — wherein the tunnels are one above the other. The TBM Eagle is on top, and Flamingo is below it. “If Eagle is taken out first, then we can proceed with the Kutchery Road station construction,” he added. While Flamingo is nearly 100 metres from Thirumayilai, Eagle is a little far, about 550 metres away.
Published – August 03, 2025 05:09 pm IST
