Metro Phase II: Construction of underground stations in corridor 3 gets under way

Construction of underground stations for Chennai Metro Rail's phase II project has begun, improving mobility and decongesting the city.

The construction of underground stations for Chennai Metro Rail’s phase II project has begun at some of the locations such as Otteri, Pattalam and Perambur under the corridor 3 (Madhavaram to SIPCOT via Thirumayilai).

The three corridors in the 116-km phase II project, which will improve mobility and decongest the city, are: Madhavaram to SIPCOT via Thirumayilai (corridor 3); Light House to Poonamallee via T Nagar (corridor 4); and Madhavaram to Sholinganallur via Medavakkam (corridor 5).

Spanning a total length of 45.4 km, the corridor 3 is the longest corridor in the phase II project. It will connect areas in the north to the south, passing through some of the busiest and dense locations across the city, including Madhavaram, Purasawalkam, Perambur, Royapettah, Thirumayilai, Mandaiveli, Adyar, Taramani, Perungudi, Thoraipakkam, and Siruseri, among several other areas.

The commencement of construction in the corridor 3 gains significance as a part of a stretch in this corridor (Madhavaram-Taramani) ran into delays in the initial stages of the project due to the cancellation and re-floating of tenders. This resulted in a delay of more than a year. Now, tunnel work along the stretch has gained momentum, and station work, too, has commenced.

According to officials of the Chennai Metro Rail Limited (CMRL), construction of underground stations is more difficult and time-consuming than elevated stations. It can take up to nearly two years to finish the construction work. “Initially, we build the diaphragm wall (or station box structure), then we move on to construct other parts of the station such as the base slab, roof slab, and concourse slab. In highly dense areas, we constantly monitor the vibration levels and make sure no cracks occur in the neighbouring buildings during the construction of the tunnel and station,” an official said.

Unlike most of the stations in the phase II project, the one being built at Pattalam (one of the areas under the corridor 3) is a stacked station, where concourse will be in the first level, upper track line in the second level and downward track line in the third level.