9 killed in collapsed tunnel; loose bolts suspected as cause

December 03, 2012

THE ASAHI SHIMBUN

Nine people were confirmed dead on Dec. 3 after a tunnel collapsed on an expressway west of Tokyo, crushing a refrigerator truck and trapping motorists inside burning vehicles, Yamanashi prefectural police said.

The accident occurred around 8 a.m. on Dec. 2, when a section about 130 meters long fell from the ceiling of the Sasago Tunnel on the Chuo Expressway in Yamanashi Prefecture. The cause of the disaster is believed to be loose bolts.

Police recovered five bodies from a van and three bodies from a passenger vehicle. The eight bodies were severely burned, according to police. The 50-year-old driver of the crushed refrigerator truck was also confirmed dead within the tunnel, police said.

Police said the three vehicles were the only ones in which fatalities resulted from the collapse of about 330 concrete slabs from the tunnel’s ceiling. The search for victims ended early on Dec. 3.

Police said they would investigate Central Nippon Expressway Co., the operator of the Chuo Expressway, on suspicion of professional negligence resulting in death and injury.

The five people in the van are believed to be three men and two women in their 20s from Tokyo. A 28-year-old woman from Miura, Kanagawa Prefecture, who was also in the van escaped but suffered burns.

The three people in the passenger vehicle are believed to be Yamanashi residents in their 60s and 70s.

According to Central Nippon Expressway officials, 23-centimeter-long bolts that are supposed to be attached to the ceiling to anchor metal plates that support concrete slabs over the expressway were found near the site of the accident.

"Based on the fact that the accident occurred 36 years after the tunnel was completed, we believe aging was the reason," Ryoichi Yoshikawa, executive officer of Central Nippon Expressway, said about the bolts.

He also said the bolts in question were never replaced and admitted that inspections of the bolts for possible corrosion were inadequate.

Company officials said workers only conducted visual checks on whether the bolts were securely in place rather than tap the parts with a hammer to detect unusual sounds that could indicate corrosion or weakness.

The hammer-tapping inspections will be conducted in other tunnels of expressways operated by Central Nippon Expressway from Dec. 3.

Transport minister Yuichiro Hata instructed expressway companies to check all 49 tunnels in Japan that have similar hanging structures.

Within the Sasago Tunnel, concrete slabs sit on metal plates about 5.3 meters long over the road. Metal pieces bolted to the ceiling hang down to hold the metal plates and concrete slabs. The bolts in the ceiling are reinforced with adhesives. The concrete slabs are also supported by mechanisms on the sides of the tunnel.

According to expressway officials, an inspection of the tunnel conducted in September involved the use of flashlights and binoculars to check on the section attached to the tunnel ceiling. No tapping of the section with hammers was conducted to check if bolts had become loose or corroded.

THE ASAHI SHIMBUN
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Workers pull out the refrigerator truck that was crushed inside the Sasago Tunnel on Dec. 3. (Jun Ueda)

Workers pull out the refrigerator truck that was crushed inside the Sasago Tunnel on Dec. 3. (Jun Ueda)

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  • Workers pull out the refrigerator truck that was crushed inside the Sasago Tunnel on Dec. 3. (Jun Ueda)
  • A passenger vehicle is pulled out of the Sasago Tunnel on Dec. 3. (Jun Ueda)
  • Rescue workers worked all night searching for victims of the Dec. 2 accident in the Sasago Tunnel. (Yosuke Fukudome)
  • An injured woman is taken to an ambulance outside of the Sasago Tunnel on Dec. 2. (Hiroshi Kawai)
  • This image, from a monitor screen of the operator of the Chuo Expressway, shows rescue workers trying to locate survivors inside the collapsed Sasago tunnel on Dec. 2. (The Asahi Shimbun)
  • The Asahi Shimbun

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