EMSD releases technical investigation report on escalator incident at Langham Place
Investigation results revealed that the main drive chain of the escalator was broken at the time of the incident. The broken drive chain device (BCD), which monitors the drive chain operation, failed to actuate the auxiliary brake to stop the escalator. Although the escalator was not overloaded at that time, the escalator reversed downward due to the weight of passengers and the loss of driving force.
An examination of the main drive chain by independent experts engaged by the EMSD verified that breakage of the chain was caused by metal fatigue. Experts also found sticky grease formed from lubricating oil and dust accumulated in the mechanical parts of the BCD, affecting the moving mechanism of the guide shoe within the device. In addition, one of the two compression springs in the BCD had been locked by a lock nut before the incident so that the spring force acting on the shoe was reduced by about half, which finally led to failure of the guide shoe to extend downward and activate the auxiliary brake.
The Deputy Director of EMSD (Regulatory Services), Mr Alfred Sit, said at the media briefing today, "Since one registered engineer and one registered worker responsible respectively for providing examination and maintenance services of the incident escalator had failed to carry out their duties, the EMSD has decided to suspend their registrations for six months."
"We have been attaching great importance to escalator safety and enforcing the law strictly. The incident involved simultaneous failure of both the main drive chain and the BCD, which is a very rare case. We shall complete the criminal investigation as soon as possible, and prosecution actions shall follow if the investigation result reveals that the incident involves illegal behaviour," he said.
After the incident, the EMSD immediately requested registered escalator contractors to conduct special inspections on all the 64 escalators with a vertical rise of 15 metres or above in Hong Kong to ensure their safety. These inspections were completed on March 31. All the escalators were confirmed to be in normal and safe working condition.
In addition, the EMSD requested the Otis Elevator Company (H.K.) Limited (Otis), the manufacturer and maintenance contractor of the escalator involved in the incident, to conduct special inspections on all its escalators in Hong Kong. These inspections were completed on April 29, in which the main drive chain of one escalator was found to have excessive elongation that slightly exceeded the replacement criterion recommended by the manufacturer. This escalator resumed normal operation after replacement of the main drive chain and inspection.
To avoid the recurrence of the escalator incident at Langham Place, the EMSD issued a circular to all registered escalator contractors and registered escalator engineers on April 7, urging them to abide strictly by the manufacturer's recommendations and the requirements of Code of Practice for Lift Works and Escalator Works compiled by the EMSD in carrying out the maintenance, inspection, adjustment and testing of the escalator components (including the main drive chain and the BCD) during their routine maintenance and periodic examination of escalators so as to ensure they are in good working condition.
In view of the fact that the high passenger-carrying capacity of escalators with a vertical rise of 15 metres or above will entail more serious consequences in the event of escalator accidents, the EMSD has stepped up sampling inspections of these escalators. A guideline was issued to the responsible persons concerned and contractors of these escalators on May 23 regarding the stepping up of periodic monitoring of these escalators.
Also attending the media briefing, the Director of Electrical and Mechanical Services, Mr Frank Chan, said, "To ensure safe operation of escalators, stakeholders from the trade and responsible persons of escalators have to dutifully exercise their responsibilities, and strictly comply with regulatory requirements stipulated under the law, while the public should also be careful when using escalators."
The technical investigation report on the escalator incident at Langham Place has been uploaded to the EMSD website (www.emsd.gov.hk/en/lifts_and_escalators_safety/publications/general_report/index.html).
Ends/Friday, June 9, 2017
Issued at HKT 18:30
Issued at HKT 18:30