"In an alley in Itaewon with a width of 3.2m, 10.7 people in 1m2 are packed... they are pushed and fall"

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The Police Special Investigation Headquarters (special version) concluded that the Itaewon disaster occurred when a crowd gathered densely at once in a narrow and steep downhill alley about 3m wide.

While announcing the results of the investigation today (13th), the special edition released the results of the analysis of the cause of the accident, which combined expert advice from the 3D simulation appraisal of the National Institute of Scientific Investigation, Kim Young-hwan, head of the Trauma Center at the National Medical Center, and Professor Park Joon-young of the National Kumoh National University of Technology.

On the day of the disaster, on October 29 of last year, around 10:15 pm, the crowd gathered at the Itaewon World Food Street suddenly 'swept' down the T-shaped narrow alley next to the Hamilton Hotel at high speed.

Because of this, several people fell at the same time in front of Pub A in this alley.

After that, the people following behind began to fall one after another.

Down the alley, people couldn't get out in the direction of Itaewon Station.

The crowd density in the back of the alley gradually increased.

As a result of the accident alley closed circuit (CC) TV and simulation analysis of the National Institute of Scientific Investigation, the crowd density in the alley increased from 7.72 to 8.39 people per square meter around 10:15 pm to 8.06 to 9.40 people per square meter five minutes later.

At around 10:25 pm, it increased to 9.07 to 10.74 per square meter.

From around 6:34 pm when the first 112 report was received, the alley where the accident occurred was able to walk in both directions, but it started to become so crowded that it was difficult to pass without contacting others.

From around 8:00 PM, a large number of people flowed through each exit of Itaewon Station.

At Itaewon Station, 8,068 people, about four times more than the number of passengers (2,129), began to get off for an hour from 5:00 pm.

From 6:00 pm to 10:00 pm, it was found that about 10,000 people got off per hour.

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At around 8:30 pm, as the crowds gathered at the World Food Street reached its peak, extreme congestion occurred around the T-shaped three-way intersection where the World Food Street and Sago Alley met.

Spokesman Kim Dong-wook explained, "Since the first overturn (fall) occurred at 10:15 pm, for about 15 seconds, people following from behind were overturned simultaneously four times."

He continued, "As the situation where the crowds from above continued to push down, until 10:25 pm, hundreds of people were piled up in layers and crushed over 10 meters," he said.

As a result, a total of 158 people died and 196 were injured in this alley.

At the time of the disaster, people were overcrowded at the site to the extent that the phenomenon of 'crowd fluid' occurred.

The rest of the people were in close contact, so they became like fluids, such as water, rather than independent particles.

Crowd fluidization has already occurred on the left and right sides of the T-shaped alley three-way intersection with crowds pouring in from both sides of the World Food Street from around 9:00 pm.

At around 10:13 pm, right before the accident, crowd fluidization became more apparent as crowds rushed down the T-shaped downhill road.

The crowd density of the World Food Street was already at the level of 9.74 to 12.09 people per square meter around 9:01 pm.

At around 10:16 pm, it decreased to 6.94 to 8.06 per square meter, but increased again to 8.06 to 9.40 per square meter at around 10:26 pm.

From 9:00 pm to 10:26 pm, a minimum of 2.68 to a maximum of 12.09 people per square meter were densely packed in the area where the accident occurred, such as the alley and the world food street.

The injured said, "I was forced to go to the accident site because of the crowd, and there was a phenomenon that came and went like riding a wave", "I kept floating in the air because of the pushing force from behind and my feet fell off", "I felt like I was being pushed away, but at the accident site I felt more powerful,” he stated at the time.

The reason for such a large crowd was analyzed into three factors: regional, place, and time.

Itaewon is a residential area with a high concentration of foreigners. Itaewon-ro alone is lined with foreign restaurants serving traditional foods from over 30 countries, clubs/lounges, and street vendors, attracting many people every year on Halloween.

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In particular, the alley next to the Hamilton Hotel has a T-shaped downhill slope and is right in front of Exit 1 of Itaewon Station, so crowds of people coming and going by subway continue to flow in.

The average road width of this alley is around 4m.

In particular, the width of the road at the point where the accident occurred was 3.199m as a result of the NFS analysis, which was the narrowest point in this alley.

An official from the special edition explained, "It is estimated that the width of the spot where the illegal structure is installed has narrowed to 3.615m, making it more difficult for people to move around the World Food Street."

The height difference from the convenience store, the lowest point of the alley at the accident site, to the World Food Street was 4.5 to 5.4 m.

The downhill slope of this alley also had an impact.

The slope of the World Food Street road is generally gentle at 0.2 to 2.257 degrees (deg), but the most gentle slope in the alley where the accident occurred is steep at 6.575 degrees.

The area around the pub, the site of the first accident, has a slope of 8.847 to 11.197 degrees.

As the Corona 19 situation has calmed down, several quarantine measures have been lifted, such as wearing outdoor masks, banning gatherings of more than a certain number of people, and restricting restaurant business hours, as one reason for the crowds, the special edition pointed out.

The victims' causes of death were compressive asphyxiation and cerebral edema (hypoxic brain damage).

It is said that he died because he was not able to breathe because he was pressed by a person.

The special edition explained that it is difficult to specify the golden time at any point in time as it is estimated that the pressure applied to the victim is not the same and the shape is different, and that the pressure is different depending on each movement.

(Photo = Provided by the Special Investigation Headquarters, Yonhap News)