Chennai Metro Rail broke through the earth at DMS on Anna Salai on Monday evening, completing the tunnelling work for the first phase of the project. There were loud cheers from engineers and workers as the tunnel boring machine (TBM) emerged into the open, close to the AGs office.
The TBM has been drilling from the Government Estate side to reach AG-DMS, 16 metres below the surface. Metro service on this stretch is expected to open in December 2018.
Anna Salai has mixed soil conditions. While Government Estate to almost Thousand Lights is clayey, Thousand Lights to Gemini is hard rock. Beyond that, until AG-DMS, the soil is clayey again, officials said.
Chennai Metro Rail Limited (CMRL) deployed 12 TBMs with a 37-km tunnelling target and the section that was wrapped-up on Monday was the most challenging, taking six years to complete.
Of the two TBMs that tunnelled on this stretch, one reached AG-DMS in mid-October. Eight of the machines, including the latest one were from Germany; there were a few from China too.
CMRL officials said work on the 4.1 km stretch from Government Estate to AG-DMS began in March 2013, and faced a series of issues including high water table and unpredictable geological conditions. “Now that this is complete, laying of track will begin and then signalling, telecommunication and electrification work too will be taken up,” an official said.
Anna Salai has faced severe traffic congestion due to the prolonged work. Yet, completion of tunnelling may not lead to the roads getting thrown open completely for traffic.
“It may take a few more months before we relay roads on this stretch and open it for traffic,” an official said.
Part of the 13-month delay arose when the contractor, Gammon India and the Russian firm Mosmetrostroy, delayed the work. Subsequently, the Russian company abandoned the project. CMRL then terminated the contract of Gammon India and awarded it to Afcons Infrastructure Limited, which resumed the tunnelling.
