Metal fatigue, failure of safety devices blamedTop News | Jane Lam Apr 20, 2017
Preliminary investigation had been completed and the results were presented by the Electrical and Mechanical Services Department at the meeting, confirming a rare simultaneous malfunctioning of the drive chain and the safety devices of the escalator.
It was reported that escalator No 18 suddenly stopped at 4.30pm on March 25 when it was moving upward.
The machine then reversed and gained speed, causing many people to lose balance and fall.
Staff from the EMSD investigated overnight and concluded that the drive chain was broken and both the broken step-chain device and auxiliary brake were not activated.
It was the first time such an occurrence happened in Hong Kong.
"The escalator has a capacity for 170 people and there were 120 people on it at the time of the accident. The drive chain should be strong enough to move those people but the metal fatigue tore it apart," said Eric Pang Yiu-hung, assistant director of the EMSD.
The probe also found that dried grease had been stuck on the slingshot of the safety devices while another spring failed to operate normally. This prevented the auxiliary brake getting triggered.
The grease was sent overseas for tests. The strength of the spring will also be tested while past maintenance work completed by the contractor will be reviewed.
The investigation is expected to finish by next month. The EMSD also promised to review the design of relative safety devices.
The department has taken a series of follow-up actions, including asking all registered contractors to carry out special inspection on the drive chain and broken chain safety device, and to test the main and auxiliary braking system of all escalators longer than 15 meters.
The main manufacturer of escalators, Otis, also promised to complete special inspections this month.