Chennai: It may take more than a 7.8 magnitude quake that wreaked havoc in Nepal to test the strength of the city’s maiden metro rail infrastructure. The row of pillars on the elevated corridor and columns of the underground network have been built strong enough to withstand easily up to 8 Richter, two decimal points more than the one that hit Nepal Saturday.Though the city is classified under moderate intensity zone III (5-5.9 Richter) in the national seismic map of the Indian Meteorological Department (IMD), all CMRL structures are constructed to zone IV standard.
“The building strength was set to zone IV specification as per NCB (National Building Code) specification despite the city falling under zone III,” CMRL (Chennai Metro Rail Ltd) project director R Ramanathan told Deccan Chronicle.“It might shake a bit. All buildings will. It happens across the world. But, CMRL’s structures will not be disturbed even if an 8 Richter quake hits the city,” he claimed explaining that the CMRL structures, unlike residences that are designed to last for 30 years, have been designed to last for 120 years and, hence, the likelihood of pressure and force exerted by natural calamities like quake and storm among others during the next century have been factored in, as was mandated in the NBC.
It is not just the pillars and columns; even the walls of the underground and elevated structures have been fortified to withstand any excess pressure. CMRL has its own set of forecast systems to plan and respond to emergencies caused by natural calamities. For instance, anemometers have been fixed atop all stations on the elevated corridor to measure wind speed. The readings will the constantly monitored by the stationmasters. This apart, CMRL has tied up with IMD to get updates on seismic activity.
In the event of a calamity, the train can be halted instantly from the operational control centre (OCC) in Koyambedu. “Electricity to the OHT (overhead traction) can be severed and all trains instantly halted by just turning off the emergency switch in the OCC,” he explained.
He added that the distance between most of the stations is only 1 km and so passengers can be easily made to alight and exit the stations during emergency easily. “Quake resistance and preparedness is on a par with international metro systems and that is why CMRL engaged multi-national general consultants (three of its five-member GC are MNCs) with metro experience. Nothing has been localised. It is absolutely safe,” said CMRL managing director Pankaj Kumar Bansal.