Loose coupling 'a serious failure'

Coupling connections between two train compartments could have come loose and caused the second serious MTR mishap in less than a month, engineers and train veterans have said.

If so, it would also be the second fault involving disconnected couplings in the city's over-a-century railway history.

The first accident occurred in 1993 on a train heading toward Tai Wo Hau station. The couplings ripped off - splitting the train into two - leaving behind one part on the railway as the captain continued forward in the other, unaware of what had just occurred.

It was the world's first railway mishap in which a running train had split. Fortunately, there were no casualties.

Online photos from yesterday's accident shows the gangway - the carriage-connecting area - being seemingly longer than usual.

The gray "accordion-style" plastic covering on the floor and wall appears to be stretched to its limit and looks to be the only material holding the two carriages together.

Lawmaker Gary Zhang Xinyu, a former engineer at the MTR, said the couplings had likely come loose, adding that it is the most serious railway fault.

"If a train separates, passengers near the splitting point could fall onto the track and the casualty would be unimaginable," he said.

"It could have been a result of faulty mechanics - loosened couplings or metal-aging. Or it could be that the train had hit something."

But Zhang added couplings are unlikely to be displaced by external objects.

"There have been frequent serious train mishaps over the past year. It worries me if it's an indication of loopholes in the MTR Corp's maintenance management," he said.

Association of Hong Kong Railway Transport Professionals chairman Henry Cheung Nin-sang said the MTRC, after the accident in 1993, upgraded couplings with additional locks on British-made M-Trains on the Tsuen Wan, Kwun Tong, Island and Tseung Kwan O lines.

But the fault yesterday occurred in a Korean-made K-Train and Cheung said he was not sure if the same safety locks are used.

However, he believes K-Trains are safe because they are equipped with an automated-brake and power-cut system which is triggered when couplings come loose.

On November 13, an M-Train running on the Tsuen Wan Line was derailed after hitting a detached metal fence, tearing off two sets of train doors as the carriage slid onto the Yau Ma Tei platform.

A similar door-ripping fault occurred last December after it hit a loose advertisement board at the Causeway Bay platform.

The mishaps incurred fines of HK$25 million and HK$3 million respectively.

jane.cheung@singtaonewscorp.com