Sunday, September 25, 2011

Signal error caused train accident?

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Kalyan Gaddameedi 7:36pm Sep 21

Investigation Into Arakkonam Collision Focuses On ‘Signal Flew Back Error’

Arun Janardhanan TNN

Chennai:After blaming the EMU driver for the Sitheri train collision that killed ten people last Tuesday, investigating railway officers are now studying the probability of a momentary malfunctioning of the signaling system. They call it the ‘signal flew back error.’
Sources said the last signal the Chennai-Vellore Cantonment EMU--which rammed the rear end of the Arakkonam-Katpadi passenger train--passed might have shown green for a few seconds, while in real it should have been red.
A ‘signal flew back error’ is when the system shows a wrong signal and turns to the right signal in a few seconds. “The driver might have seen the wrong signal, and by the time the signal corrected itself, the engine would have passed it,” the official said.
According to railway’s first inquiry report on the Sitheri accident, signals between Arakkonam and Sitheri had shown the right colours. “We found that the signals after Arakkonam station showed ‘attention’ (double yellow) and ‘caution’ (single yellow) alerts as a passenger train was on hold about 7km ahead on the same line. But the last signal is suspected to have shown green due to the error, and the driver might have increased the speed,” the official said.
An official in the signal and communication department of Southern Railway said lightning or minor glitches in the network can cause such an error. “From the data we have collected from all the signals along the stretch, it looks like a system error is probable. The driver has had enough experience and seemingly no intention to commit an accident,” said a higher official of Southern Railway.
Officials compare it with a recent train accident near Beijing in China where a bullet train ploughed into the back of another that had stopped due to a signal error. “There the signaling device malfunctioned due to lightning and failed to turn from green to red,” said the official.
A day after the accident, A Rajkumar, motorman of the EMU, had told TOI from his hospital bed that he did not violate signals. Later, he told railway investigating officers that the first three signals were yellow, but the last one showed green. This, he has reportedly told officers, was when he increased the speed.
Officials, who initially blamed him for the disaster, are now taking his statement seriously as the ‘signal flew back error’ theory has gained credence.
Additional divisional railway manager John Thomas said commissioner of railway safety S K Mittal is going through the signal records. The inquiry report is expected to be out in four days.

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