Light House to get Chennai Metro Rail Limited’s first shallow underground station – The Hindu

Chennai News

The building has been designed specifically to avoid disturbance to the marine ecosystem

The building has been designed specifically to avoid disturbance to the marine ecosystem

In a couple of years when people plan to visit the Marina beach, they will be able to reach it by taking the Metro Rail and disembarking at the Light House station, which will be the longest station of phase II, built over 300 m.

Here, unlike in other stations, passengers will go to level 2, get a ticket and then come up to level one to board the train. Additionally, this is the first shallow underground station built by Chennai Metro Rail Limited (CMRL), specially designed with the platform on the first level and a mini-concourse in the second. This is the first time CMRL will forego the usual building plan of its underground stations — a concourse on the upper level and a platform on the lower.

This is an important terminal station for the stretch between Light House and Poonamallee, and when it comes up, residents from across the city will have easy and quick access to Marina beach. CMRL has already obtained the Coastal Regulatory Zone (CRZ) clearance necessary for the station’s construction.

According to officials of CMRL, they planned it as a shallow underground station to ensure the marine ecosystem was not affected. “In this location, unlike in other stations, where we go as deep as 20 m, the maximum depth will be 15 m. Also, the concourse is coming up on the second level and the platform on the first level, whose depth will be about 12 m. This is because we did not want to use the tunnel boring machines below the 12-m mark,” an official said.

While one entry/exit will come up near Queen Mary’s College, another will be built near Light House, and the concourse will be quite small, just about 70-80 m long, resembling a subway. The entry/exit structures will be aesthetically designed to give a view of the beach as well.

“While the platform itself will be 140 m, the whole station length totals to around 300 m because it has to accommodate facilities like stabling and crossover (where trains switch between tracks),” another official said. Also, to operate the system even in case of heavy rains or flooding, the entry/exit structures will have flood gates, and the tracks will have sumps to pump out any water seepage.

Officials said they would take a host of steps during construction as it would be pretty tough to build an underground station due to the sandy soil.

“We have to take measures so that the soil does not collapse. For that, we have to create a trench, increase the density of bentonite (a substance used in construction as a binding material) and use bentonite slurry, do concreting, lower the reinforcement cage and then build a diaphragm wall (a station box),” the official added.