Monday, July 22, 2024

Tunnel Boring Under Adyar River for Metrorail Phase Two Set to Begin Next Week

Commencing next week, the tunneling initiative beneath the Adyar river is set to kick off as part of the second phase of the metrorail project. The tunnel boring machine, named Kaveri, initiated its tunneling journey from the Greenways Road metro station towards the Adyar junction metro in February. Having covered 800m, the machine has successfully tunneled 300m and is currently in close proximity to the Adyar river.

This particular stretch, connecting the Greenways Road metro to the Adyar Junction metro, is integral to the 45.4km corridor-3, spanning from Madhavaram Milk Colony to Siruseri Sipcot. The overall 118.1km phase-2 is anticipated to be operational in phases between 2025 and 2028.

According to T Archunan, the CMRL project director, the tunnel boring machine (TBM), named Kaveri, is poised to construct a tunnel approximately 20m deep beneath the Adyar river, spanning a distance of 400m. The crown of the tunnel, denoting its apex, will be situated 7m below the riverbed.

Scheduled to commence tunneling under the Adyar riverbed on Monday, the TBM will navigate through this section at a careful pace. Initially progressing at a speed of 1.5m per day due to the presence of various structures along the route, including a petrol bunk and a college, the TBM’s speed might further decrease to 1m per day as it enters the riverbed. This cautious approach is necessary to avoid potential damage or cracks to the structures above.

Experts have highlighted the challenges associated with tunneling under a water body, emphasizing the consideration of water pressure during the planning stages. The tunnel walls will be constructed with a thickness of 35cm, but adjustments may be made, increasing it to 40cm or 45cm if necessary, depending on the pressure beneath the river. Additionally, the tunnel boring machines are equipped to waterproof and seal the gaps between segments and rings in the tunnel, mitigating the risk of seepage, as explained by R Ramanathan, a former CMRL official.

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