<Anchor>
As I said yesterday (29th), the soundproof tunnel where the accident occurred was made of a material that burns easily.
Because of this, flames and black smoke quickly spread in the tunnel, causing more damage.
If so, reporter Kim Ji-wook pointed out why it was possible to use materials that burn easily and whether there is anything that needs to be changed institutionally.
<Reporter>
Near the Geumha Underpass on the Western Expressway.
A soundproof tunnel with a length of 420 m is located at the junction.
These long soundproof tunnels can be seen all over the road.
Most of them are made of plastic material that bends and catches fire like this.
Currently, there are a total of 55 soundproof tunnels nationwide managed by the state, including 25 on privately funded highways and 9 on national highways.
Tunnel-type sound insulation panels usually use one of three materials: PMMA, also known as acrylic, polycarbonate, also known as PC, and tempered glass.
The material used for the soundproof tunnel that caught fire yesterday is PMMA, which is the most vulnerable to fire.
This is the 2018 tunnel-type soundproof facility fire safety report by the Road Traffic Research Institute.
When the three materials were heated for about 13 minutes, tempered glass remained intact until the end of the experiment, while PMMA burned all materials and even caused a secondary fire on the floor.
The researchers concluded that PMMA material was unsuitable for use in acoustic tunnels.
[Donmuk Choi/Professor of Facility and Firefighting Engineering, Gachon University: Because it is a plastic material, it is easily combusted, and a lot of smoke or toxic gas is emitted, so there are many problems such as human casualties.]
Even so, the reason why acrylic materials are used is tempered glass .
This is because it has a high light transmittance compared to light, does not spoil the aesthetics, and is decisively cheaper.
Among the government-managed soundproof tunnels, PMMA materials were used in six places, including yesterday's tunnel.
(Video coverage: Cho Chang-hyun · Kim Tae-hoon, video editing: Kim Jun-hee)
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