The exact cause of the fire will have to be investigated, but now it seems that the fire spread rapidly through the ceiling of the soundproof tunnel made of a flammable material, and the number of casualties increased.
Reporter Park Ha-jung pointed out the possibility of increasing human casualties based on the situation inside the tunnel.
[Is it moving, fire?
To the right.]
The soundproof tunnel where the fire spread, nearly half of its 540m length was burned.
[Lee Hee-jun / Witness: I heard the sound of the explosion in a chain, so I looked outside and saw a lot of black smoke rising, and the fire continued to grow toward the glass roof on the side...
The material for this soundproofing tunnel was PMMA, a plastic often referred to as acrylic.
It has good light transmittance, allowing sunlight to enter well, but it also has the characteristics of being easily burned.
About 2 years ago, in Suwon, Gyeonggi-do, a fire that started from a single vehicle burned down a plastic soundproof tunnel about 50m long.
[Lee Song-gyu/President of Korea Safety Professionals Association: The vehicle may explode secondarily.
For soundproofing (facility) materials, non-combustible or flame-retardant materials should be used.]
The reason why the damage was increased was that the whole section was made by connecting hundreds of meters.
[Lee Young-joo/Professor, Department of Fire and Disaster Prevention, University of Seoul: Since it is a continuous tunnel, people have to evacuate a long distance in the process of evacuating...
When I looked inside the tunnel after the flames were extinguished, most of the vehicles in the accident were concentrated in the opposite lane of the truck that was on fire.
All four vehicles that died were found in the opposite lane.
Fire trucks and ambulances, which went out to evolution and rescue, also had difficulty entering as the lanes were blocked by damaged vehicles.
In situations where it is difficult to secure visibility in smoke and toxic gas, the possibility of secondary accidents such as collisions increases.
Fire authorities are not ruling out the possibility that deaths may have been caused by suffocation due to smoke inhalation.
The soundproof tunnel, which was normally illuminated by light, turned into a dark tunnel where the exit was unknown when the fire broke out.
(Video coverage: Hwang In-seok · Kang Dong-cheol, video editing: Park Ji-in)