After two years, Chennai Metro Rail’s tunnel from Greenways Road to Mandaveli to be completed in October

After a protracted delay, the tunnel boring machine (TBM) ‘Noyyal’ will finally complete the tunnel between Greenways Road and Mandaveli in October for Chennai Metro Rail’s phase II project.

Greenways Road to Mandaveli is a small underground stretch and a part of corridor 3 of the phase II project that runs from Madhavaram to SIPCOT via Mandaveli for 45.8 km.

In September 2023, ‘Noyyal’ began its mission at Greenways Road Metro Rail station site to create a near 750-m tunnel till Mandaveli. Behind it, the TBM ‘Vaigai’ too followed suit. According to officials of Chennai Metro Rail Limited (CMRL), there were a few reasons for the delay in completing the twin tunnels between Greenways Road and Mandaveli. Initially, CMRL officials estimated that in six months, the tunnels could be completed.

But one of the biggest challenges was shifting of utilities to build the diaphragm wall of the Mandaveli station.

‘Major challenges’

“We had to shift four massive water and sewer pipelines to build the diaphragm wall. For building a shaft of the station, we had to divert the utilities and then restore it to the original location. There were two major water pipelines we had to move, with one being 800 mm in diameter and the other being one metre in diameter. Also, two big sewer lines which were of 900 mm diameter and 1.2 m diameter had to be shifted. For the diversion of these pipelines, a pumping well had to be constructed too. It was much more difficult than what we had expected and hence took a long time,” an official said.

‘Delay by contractor’

Since Mandaveli is a junction, the diversion of these utilities was even more challenging. The last part of the diaphragm wall is being built and will be finished shortly. “The contractor building the station too delayed the work. But we did put pressure, and work will be finished shortly,” another official said.

Due to the delay in the construction of the Mandaveli station, the TBM has been stationed outside the station for a while now. The breakthrough in Mandaveli is expected in about two-three weeks. By 2028, train operations from Greenways Road to Thirumayilai via Mandaveli are scheduled to be opened to the public.