Chennai Metro Rail floats tender for 5.8 km underground stretch

Chennai Metro Rail Limited (CMRL) has once again invited bids in 2021. The bids are for Phase-II 5. 8 km underground stretch between Kolathur and Nathamuni. It is also considered to be one of the most difficult underground stretches.

The rocky soil condition of the stretch is what makes it challenging. The first tender had been floated for the same in January last year. It is a part of the six construction tenders that were canceled due to various reasons including not having many proposals or proposals being higher than the estimated price. The total Phase-II underground stretch of 118.9 km will be approximately completed by the end of 2025.

On corridor 5 between Madhavaram and Sholinganallur, there is only a single underground stretch of 5.8 km between Kolathur and Nathamuni. The CMRL has sent invitations for the construction of underground lines along with the twin tunnels for upline as well as a downline. The duration of the project completion will be 3.8 years.

The initial soil investigation by CRML stated that the soil conditions are the reason why the construction is going to be tough.

The soil is mainly like black granite or like quartz or charnockite. The tunnel boring machines need to be operated at a suitable speed of 8 meters every day. And it is going to be a challenge for the engineer. Otherwise, the surrounding buildings can suffer. The depth of the tunnels is going to be between 15 meters to 21 meters.

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