Tunneling across densely populated zones in Chennai a big challenge for metro rail: expert

Chennai:

Metro Rail will be digging nine metres below the densely populated Washermenpet- 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 will be geo technically monitoring the work along with crackmeters.

“Although the tunnel technology is improved but it will be a biggest challenge for tunneling experts as the tunnel criss crosses many heritage sites and thickly populated areas.

Currently, metro rail is building diaphgram chambers for the underground stations and tunneling work has started in only one site, Ramanathan said. The biggest challenge is also to ensure that water does not seep into the structure, he added.

Interestingly, the underground stations will have four entries from the road to station. The stations will have the capacity for four cars but initially metro rail plans to operate with four cars, Ramanathan said. He also said Chennai will be the first city in India to have platform screen door facility. Platform screen doors (PSDs) at train or subway stations screen the platform from the train. They are a relatively new addition to many metro systems around the world, some having been retrofitted to established systems

He suggested the city should follow metro protection zone model of Hong Kong and Singapore where no development works would be carried out in the metro zone. Currently, New Delhi is implementing it, he said.

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

Ramanathan also said that Chennai Metro rail will be following the standard guage. “In case of Delhi Metro there was some confusion over which guage to use and initially in the first phase, broad guage was preferred. Later they went for standard guage which is more suitable for metros which criss-crosses across the city,” he added.