Shrugging off initial delays, Chennai Metro Rail corridors 4 and 5 on fast track

CHENNAI: The double-decker Metro construction (part of corridor 4) is progressing well, despite several initial delays. From land acquisition to heavy utility diversions, the Chennai Metro Rail Limited (CMRL), along with the contractor, had to spend many months on preparatory works.

This particular double-decker construction will be the first in India to have both Metro lines supported on the same pier.

This stretch will have 4 stations developed at two levels –Alwarthirunagar, Valasaravakkam, Karambakkam and Alapakkam – and there will be a common concourse (ticketing level) with ‘island platforms’ (railway tracks on either sides) operating for 5 km. L&T was awarded the tender for the construction of corridor 4.

Around 99% of the piling work and 78% of pile cap work has been completed. The elevated corridor viaduct spans 3.75 km, which features a double-decker structure.

CMRL officials said that this double-decker construction was one of the most challenging lines to construct due to design, lack of space and importantly, diversions of many dry and wet utilities in the stretch. Corridor 5 merges at pier 110 of corridor 4, where the double-decker begins and de-merges at pier 242.

“With 192 piers between 110 and 242, the construction is going on at a fast pace,” added the official.

Cranes could not be used for erecting the U-girders from piers due to lack of space. Hence, launching girder (LG) was used to erect the U-girder from pier 234 at Alapakkam. The LG successfully completed the erection of U-girders in 13 spans (center to center distance between two piers) with approximately 52 U-girders.

Officials of both CMRL and L&T stated that construction works were progressing at a fast pace despite the challenges. Speaking to DT Next, an official said, “Till today, we’ve successfully erected 27 spans on both levels of the double-decker corridor 4 and 5 pier caps, and are now ready for U-girders installation. Additionally, the corridor 5 level pier works are also progressing well.”

For the service line that allows the movement of rolling stock, the work is going on from corridor 4 to 5. “Till now, 26 out of 35 piers have been completed up to corridor 4 level in service connection, and 15 level pier arms have been erected,” added the official.

Furthermore, in Alapakkam station, substantial progress has been made with 11 piers now standing tall, marking the successful installation of the upper platform pier arms. In Karambakkam station, all the concourse level piers casting have been completed and level pier arms installation is in progress. In Valasaravakkam and Alwarthirunagar stations, pier works are going on.

In the case of stations’ entry and exit works, in Alapakkam station, works on the underground sump-and-pump room and the roof slab are progressing at a fast pace. “The raft foundation works of the underground sump-and-pump room are completed. Wall works are going on in Valasaravakkam station, and excavation works of underground sump-and-pump room are going on in Karambakkam station,” he explained.