Tunnelling in populated areas a challenge for CMRL

Metro Rail will be digging nine metres below the densely populated Washermanpet-Manali stretch and it will be one of the most challenging tasks, according to an expert.

Delivering the N V Arunachalam Memorial Endowment lecture, chief engineer (cut and cover structure) M Ramanathan, whose Hong Kong-based firm AECOM is handling the Chennai Metro rail project, said experts would be geo-technically monitoring the work along with crackmeters.

“Although the tunnel technology is improved, it will still be the biggest challenge for tunnelling experts as the tunnel criss-crosses many heritage sites and thickly populated areas.”

Currently, the Metro Rail was building diaphragm chambers for the underground stations and tunnelling work had started in one site only, Ramanathan said. The biggest challenge was also to ensure that water did not seep into the structure, he added.

He also said that the other major problem the tunnelling experts faced was the dry wells in the residential areas. These wells in the alignment of tunnels required to be backfilled, he said.

He also said Chennai would be the first city in India to have platform screen door facility. Platform screen doors (PSDs) at train or subway stations screened the platform from the train. They are a relatively new addition to many metro systems around the world.