The authorised examiner (AE) looking into the Tah Ching Road lift accident which left an elderly woman with her hand severed has delivered his final investigation report, announced the Building and Construction Authority (BCA) on Friday (Nov 6).
In his findings, the AE said that the "door protective devices cannot be proven reasonably to have failed to function properly on the day on the incident".
"It was clear that during the evacuation operations conducted by SCDF, the lift doors had clearly responded to obstructions several times when SCDF officers were in the door way at 7.26am, time stamped by Police CCTV footage," he added.
The AE also said that the doors were tested following the incident and that they worked according to their specifications.
With that in mind, the AE has recommended that efforts to educate the public on the safe use of lifts be stepped up, and that there should be a review of the settings of various safety devices in lifts, such as door protective devices.
The BCA said it accepted the recommendations of the AE's report, and will work closely with the industry and lift owners of both public and private buildings to raise awareness on precautions to observe when using lifts. This includes the need to keep small and thin objects - such as a dog leash or dangling straps of backpacks - away from the lift doors.
"FULCRUM ACTION" CAUSED GAP AT BASE OF LIFT CABIN DOORS
In his report, the AE reconstructed the sequence of events based on CCTV footage, the specialist medical report, interviews and other evidence gathered, on top of inspections and tests on the lift, as well as simulations of how the accident could have happened.
The AE found that during the incident, the victim Mdm Khoo Bee Hua, 85, was inside the lift, and the lift doors had closed while her dog was still outside. At that point, one end of the dog's leash was looped around Mdm Khoo's left wrist, trapping the leash between the closed lift doors, with the dog outside.
The lift started to ascend, tightening the leash and likely pulling Mdm Khoo to the ground, said the AE. The dog was also pulled upwards against the lift lobby doors, until its harness buckle was caught at the top of the lift lobby door.
This pull of the taut leash, based on simulations, could have caused a "fulcrum action" that opened up a small gap at the base of the lift cabin doors, the report said. Mdm Khoo's left hand would have then been pulled through the gap.
Mdm Khoo's left hand was partially pulled through the lift cabin doors, and was crushed and severed between the lift cabin doors and the internal parts of the lift lobby doors before the lift came to a gradual stop close to the third storey. "The lift came to a gradual stop as the opening of the lift cabin doors triggered the emergency stop feature," said the AE.
The severed hand then fell to the bottom of the lift pit once the dog leash was released.
PROTECTIVE DEVICES COULD NOT DETECT LEASH
As the dog's leash was only 2mm thick, the door protective devices were unable to detect it as an obstruction in the lift doorway, said the AE. The protective devices are not designed to detect objects less than 10mm thick.
When activated, the protective devices are designed to re-open or remain open if there is an object that hits the safety edge and triggers the control to stop the door from closing, or if there is an object that is blocking the infra-red sensor.
All door protective devices were tested and verified to be working according to specifications, said the AE. During the rescue operation by the Singapore Civil Defence Force, the lift doors were also seen to have responded to instructions.
The BCA said its own investigation was consistent with the AE's conclusions. The authority also said it has updated Mdm Khoo’s immediate family members of the findings of the investigations.
Calling the incident "a very unfortunate one", the BCA said: "We are saddened by what has happened to Mdm Khoo and hope that she recovers well from this traumatic experience."