Falling 'Bultongbi' Increases Damage... "Plastic in Soundproof Tunnel More Dangerous Than Oil" Alternatives

Soundproof Wall PMMA 'Liquefies' at 100 Degrees
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Need to Indicate 'Distance from Exit'

[Asia Economy Reporter Lee Ji-eun] Regarding the fire in the noise barrier tunnel on the Gwacheon 2nd Gyeongin Expressway, which resulted in 5 deaths and 37 injuries, an analysis has emerged that the rapid spread of the fire was due to the characteristics of the plastic noise barrier material. To prevent recurrence, it has been pointed out that it is necessary to change the material or structure of the noise barrier and to mark the distance from the exit.

Professor Lee Yong-jae of the Fire Safety Management Department at Kyungmin University appeared on CBS's 'Kim Hyun-jung's News Show' on the 30th and said, "The reason it spread so quickly overall can be seen as a problem with the material acrylic. Simply put, plastic." On the 29th, the fire started from a waste transport truck driving on the road and spread significantly as it caught onto the noise barrier tunnel made of a type of acrylic called 'Polymethyl Methacrylate (PMMA)'.

[Image source=Yonhap News]

Professor Lee explained that the flash point (the temperature at which it ignites) of acrylic materials such as plastic is about 280 degrees Celsius, but they have the property of turning into a liquid state at around 100 degrees Celsius. This is the identity of the 'fire spark rain' witnessed in the accident footage. The burning acrylic turned into a liquid and melted.

He said, "This (fire spark rain) fell along the tunnel," adding, "In a way, it is more dangerous than oil. Oil just burns up a fixed amount and that's it, but plastic, when ignited in a gel (liquid) state, has the property of burning for a very long time until it is completely consumed." He explained that the plastic, liquefied and spreading over a wide area, burning caused the scale of the damage to increase.

The closed structure of the noise barrier tunnel was also analyzed as one of the causes that increased the damage. The plastic noise barrier tunnel is a long tunnel that wraps the road in a rounded roof shape. Professor Lee said, "If it were an open type, even if heat comes from vehicles, the smoke or heat could rise and escape upwards, but because this is a sealed structure, heat and smoke accumulated."

President Yoon Suk-yeol, after hearing the news of the accident, ordered the preparation of measures to prevent recurrence and an emergency inspection of similar facilities. There are 52 similar noise barrier locations nationwide. To prevent recurrence, changing the material of the noise barrier is first being considered. Professor Lee said, "There are noise barriers made of metal or glass, but these are basically somewhat more expensive."

Another method that can be considered is creating passages for smoke to escape. Professor Lee said, "There are cases like this abroad, and as an alternative, (the tunnel) is segmented," adding, "Whether at 100m intervals or some other spacing, even if a fire occurs, it will only spread within the segmented section, and heat or smoke can be easily discharged outside through the segmented parts."

Professor Lee also proposed marking the distance from the exit at various points inside the tunnel. He said, "I hope there will be signs like 'X meters from the exit,'" adding, "If there are meter markings at regular intervals indicating whether the accident point is closer to the entrance exit or the exit side, it can be a great help in responding to emergencies."

This content was produced with the assistance of AI translation services.