By Ninad Siddhaye www.dnaindia.com
Will an elevated metro running with a pantograph and other Over Head Equipment (OHE) pose a threat to commuters in the trains as well as to motorists plying under it? If the officials of the Mumbai Metropolitan Region Development Authority (MMRDA) are to be believed, then the threat is very much real.
As per an internal report of the MMRDA, safety is a major concern. “Earth is a good conductor of electricity, but not concrete. The resistance of the concrete is much higher than the earth. The resistance will depends on the cracks in the concrete, moisture content, age of the concrete and the point at which the conductor comes in contact with the concrete.
If the parted 25kv AC conductor falls on the concrete and the fault is not cleared by the circuit breaker, dangerous condition will arise,” says a MMRDA communication to Mumbai Metro One Pvt Ltd (MMOPL)—the Reliance Infrastructure-led consortium which is constructing the first metro line between Versova and Ghatkopar.
“If the parted conductor hangs below the viaduct, it will endanger the safety of road users. If the parting takes place above the railway crossing and the power is not switched off, wrong phase coupling can result,” says the communication.
MMRDA officials have had talks with MMOPL about replacing the overhead electrification with an underground system called the third rail.
Admitting that the present system has some loopholes, MMRDA metropolitan commissioner Rahul Asthana told DNA that the authority has already initiated talks with the Mumbai Metro Transport Pvt Ltd (MMTPL)-another consortium led by Reliance Infrastructure, which is constructing the 32-km long metro-II between Charkop and Mankhurd to replace the overhead system with third rail. “However, not much can be done about the first line since the work has gone too far ahead,” said Asthana.
Explaining the grave danger that a pantograph can cause, the communication says that a pantograph entanglement often results in the breaking of parts like nut bolts, copper strip hoses. “Sometimes, even the entire pantograph gets uprooted. These parts often get thrown off. If these parts fall outside the viaduct, they can endanger the safety of road users,” it says.
Another important aspect of the dangers mentioned in the communication talks about internet cables as well as cables for the TV connections. “25kv can induce voltage in internet cables, TV cables and metallic structures like grills etc. Adequate study is needed,” says the communication.