Sensors may have led to accident

Platform doors on Seoul Metro line No. 5 at Gimpo International Airport Station in Gangseo District, western Seoul, were found to have a structural defect that may have led to the death of a 36-year-old passenger on Wednesday.

The passenger, surnamed Kim, was dragged and killed by a departing subway train after he got trapped between the platform door and the train.

Details of how the accident happened are starting to get clearer, although not entirely so.

Apparently the passenger tried to exit the train but the platform doors had already closed. Then the train doors closed and we was caught outside them. Another passenger on the train made an emergency call via an intercom and the train’s engineer responded by reopening the train’s doors for roughly 27 seconds.

He assumed that the stuck passenger would have returned to the train, but he did not. He remained trapped between the train and the platform door as the train pulled out of the station.

The National Forensic Service said an autopsy revealed Kim’s immediate cause of death as multiple organ damage from the shock of being dragged by the train.

According to Seoul Metropolitan Rapid Transit (SMRT), there are sensors to detect movement inside platform doors to keep them open while passengers get on and off trains. But once all doors are closed, the sensors deactivate. This is true for all platform doors on lines 5 through 8.

“Sensors are designed to switch off,” said an official from SMRT, “to prevent them from picking up irregular reflections from subway trains’ stainless steel.” But sensors on lines 1 through 4 are operated for five seconds after the platform doors close.

Another official from SMRT said, “There were frequent problems with platform doors at Gimpo International Airport Station, for which we have made improvements. But last month, we decided to replace all platform doors before next September.”

The engineer in charge on the day of the accident said during police questioning, “There was no need to reopen the platform doors because I thought Kim would get back on the train once I opened the doors of the train.”

Police found a witness on Thursday but didn’t reveal details of the questioning. Police will try to figure out how Kim got stuck between the platform door and the subway train, and why he didn’t go back into the train when he could.

BY CHO HAN-DAE AND SEO JUN-SUK [kim.yuna1@joongang.co.kr]