CHENNAI: The doors of the underground Chennai Metro Rail Limited (CMRL) stations can withstand any inferno for nearly two and a half hours, according to an official. Talking to reporters after showing the efficiency of tunnel ventilation during a smoke drill, VK Singh, Chief General Manager, Underground Construction, and J Hariprasad, Joint General Manager, Tunnel Ventilation, told Express that in the event of a fire, the tunnel has the mechanism to clear the smoke on the metro track within a mere three minutes.
“If a fire breaks out between Thirumangalam and Anna Nagar Tower Station, there are four fans dedicated to the station as well as four on the tracks which will work out a mechanism to stave off the smoke through the four ventilation shafts in the station,” Hariprasad said.
“The shafts are programmed in such a way that one takes out hot air while the other takes in cool air,” he added.
The high decibel fans, with a speed of 1400 revolutions per second, can suck out 45-120 cubic metres of smoke per second, Hariprasad said. In order to cut down the noise pollution as per the Indian Standard of Acoustics, each fan has two silencers.
Aside from that, the station has sensors which monitor heat, smoke, fire and visibility. All stations are controlled from Koyambedu through the operation control centre. However, each underground station will have a station control room which monitors the air conditioning, fire alarm and security.
Since power is the key to the entire operation, the CMRL has ensured that even if the grid fails they have a diesel generator as well as a UPS that can run the operation for at least eight hours. The power is supplied through three grids located in Alandur, Koyambedu and Chennai Central. Each station has a diesel generator as a backup in the ancillary building and a UPS battery.
“We have standby power systems at the operation control centre in Koyambedu as well as at the nearby station. In case, due to any technical glitches, we can even operate the standby power system from the control room of the station,” an official said.