CMRL phase 2: 11th tunnel breakthrough after delays, tough terrain at Perambur
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Chennai: The metro rail phase 2 project on Tuesday achieved its 11th
tunnel breakthrough
as
tunnel boring machine Kalvarayan
(S 1331) emerged at
Perambur
south shaft after completing an 867m up-line drive from Ayanavaram. While the event marked technical progress, it also drew attention to the challenges and delays affecting the 9km underground stretch between Madhavaram and Kellys.Awarded to Tata Projects Limited, this stretch involves building twin tunnels using seven tunnel boring machines (TBMs).
Kalvarayan's drive was delayed for months due to pending construction at the Perambur underground metro station. Both Kalvarayan and another TBM had to remain idle during this period.The station construction encountered issues after initial tenders were scrapped when contractors quoted excessively high rates. The retendering process pushed the project deadline from Dec 2027 to July 2028.Even after work resumed, engineers faced a major obstacle water seepage from below the existing diaphragm wall at the station. To tackle the leakage, Tata Projects had to construct two to three additional diaphragm walls.The Ayanavaram-Perambur tunnel then presented other technical difficulties. Kalvarayan had to tunnel under active railway tracks and platforms at Perambur railway station and pass through densely populated residential zones. Along the way, engineers had to protect more than 32 borewells. CMRL (
Chennai Metro Rail
Limited) arranged alternate water sources in advance to avoid public inconvenience.Throughout the tunnel drive, advanced instrumentation was used to monitor ground settlement, ensuring safety and structural stability. All operations were carried out within prescribed limits, avoiding disruption to surface infrastructure and rail operations, said an official release.Despite these setbacks, CMRL maintains that overall progress remains on track.
Officials said that non-civil components such as utility relocation and interior work can be completed quickly, and they aim to meet the final operational target of July 2028.
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