Six tunnel boring machines (TBMs) deployed by the Chennai Metro Rail Limited (CMRL) are currently lying idle beneath city roads, stuck in limbo due to delayed construction of underground stations at Moolakadai, Perambur, and Mandaveli.

The TBMs, launched as part of Corridor 3 of the Phase II Metro project from Madhavaram to SIPCOT, have reached their designated stations but are unable to proceed as the station boxes are incomplete. Without a completed diaphragm wall or station box, the machines cannot break through or be dismantled for reuse.

According to CMRL officials, the root of the delay traces back to a decision made four years ago, when six tenders for underground station construction along this corridor were scrapped due to high and unreasonable bids. Reissuing the tenders caused a significant time lag, directly affecting the tunneling schedule.

"Though the TBMs started work on time, they were held up because the station construction lagged behind," a CMRL official stated. "Now, the tunneling is done — the machines are just waiting for the stations to catch up."

Two TBMs are stuck at the Moolakadai station, two at Perambur, and two near Mandaveli. They had originated from Madhavaram High Road, Ayanavaram, and Greenways Road, respectively.

In addition to tender issues, officials cited challenges like shifting utilities, relocating borewells, and obtaining traffic diversion permissions as factors that hampered progress.

However, there’s a glimmer of movement ahead. "From next month, the TBMs will gradually begin making breakthroughs, and all six are expected to be out before the end of this year," the official confirmed.

Until then, the machines — each weighing hundreds of tonnes — remain idle beneath Chennai, symbolizing how tendering missteps can slow the wheels of urban transit development.

Image source:themetrorailguy