Japan has ordered inspections of ageing highway
tunnels after a collapse in Yamanashi prefecture that killed nine
people, as suspicion over the cause of the accident centred on decaying
ceiling supports.
The government pledged a thorough review on Monday and said
"significant investment" would probably be required in the motorway
network, parts of which, including the accident site, were built during
the economic boom of the 1960s and 1970s.
"As a major factor, we suspect ageing," an official from highway
operator NEXCO said, referring to the tragedy at the Chuo Expressway's
Sasago tunnel, which passes through hills near Mount Fuji, 80km west of
Tokyo.
Footage from inside the tunnel showed concrete panels had collapsed
in a V-shape, possibly indicating some kind of weakness in the central
supporting pillars suspended from the roof, experts said.
Engineers on Monday began inspections at three other tunnels in the region with the same design, as well as at Sasago.
Rescuers earlier found three more crushed bodies, taking the death
toll to nine. At least three vehicles were buried on Sunday when
concrete ceiling panels crashed down inside the nearly 5km tunnel.
Five blackened bodies were found inside a single vehicle and
emergency workers also recovered the body of a lorry driver, identified
by broadcaster NHK as Tatsuya Nakagawa, 50, who had telephoned his
company to ask for help.
Later, the bodies of an elderly man and two elderly women were also
recovered from a crushed vehicle, Kyodo News said, as attention turned
to what caused the collapse.
Deterioration suspected
An official from highways operator NEXCO said material degradation
was a possibility, adding the risk of further collapse remained although
the ceiling had undergone its regular five-yearly inspection in
September this year.
Chikaosa Tanimoto, professor emeritus of tunnel engineering at Osaka
University, told that NHK the support panels were suspended from
pillars.
"It is conceivable that the parts connecting the ceiling panels and
pillars, or pillars themselves, have deteriorated, affected by
vibrations from earthquakes and passing vehicles," he said.
Earthquakes are common in Japan, though none was reported in the area at the time of the collapse.
Emergency workers equipped with breathing apparatus on Sunday battled
around a third of the way into the tunnel, where they found 110 metres
of concrete panels had fallen, crushing several vehicles.
But hours later engineers gave warning the structure could be
unstable, forcing rescuers to halt their work as a team of experts
assessed the danger.
Dozens of people on Sunday abandoned their vehicles on the
Tokyo-bound section of carriageway, and ran for the exits where they
huddled in bitter winter weather.
One man who fled the tunnel told Jiji Press he had watched in horror
as concrete crashed down onto a vehicle in front of him, leaving little
more than a mound of dust and debris.
Footage from security cameras showed large concrete panels had fallen, apparently having collapsed from the middle.
Japan has an extensive web of highways with thousands of tunnels,
usually several hundred metres long. Millions of cars use the network
every day. |
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