03/12/2012 16:56
Japan officials: Missing bolts may have caused tunnel collapse
The mangled wrecks of cars being carried out of Japan's Sasago Tunnel suggest there was little motorists could do to escape the sudden collapse of the ceiling above them.
A day after the disaster, one main theory has emerged as to what caused the collapse, which killed nine people who were trapped in their cars by rubble or the flames that broke out shortly after.
At a press briefing on Monday, the executive officer of the tunnel's operator said it appeared that some "anchor bolts" used to secure concrete slabs to the tunnel ceiling were missing.
"There were parts of concrete (slabs) where bolts had fallen off," Ryoichi Yoshizawa said, according to a spokesman for Central Japan Expressway Company or NEXCO-Central.
"The aging of the bolts or the concrete slabs could be a potential cause (of the collapse)," Yoshizawa said CNN. He did not say how many bolts were found to be missing or how they came to be loose.
Yoshizawa added that while regular checks had been performed on the tunnel, they were visual checks and there was no physical testing.