At least nine people have died following a collapse in the Sasago Tunnel on the Chuo Expressway, one of the major motorways connecting Tokyo to central and western Japan.
Reports indicate that a section of the tunnel, around 130 metres long, and weighing about 360 tonnes, collapsed at 8 a.m. on Sunday, sending panels of reinforced concrete crashing down onto the traffic.
One car caught alight, and the tunnel was rapidly engulfed in flames and smoke as fuel from ruptured petrol tanks fed the fire. According to authorities, it took fire-fighters three hours to extinguish the blaze, but smoke reportedly continued to be seen coming from the tunnel later in the day.
Survivors described chaotic scenes. “When I was driving in the tunnel, concrete pieces fell down suddenly from the ceiling,” one motorist told public broadcaster NHK. “I saw a crushed car catching fire. I was frightened, left my car and walked for about an hour to get out of the tunnel.”
Another woman, who was in a car of six people crushed by a slab of concrete, said: “I could hear voices of people calling for help, but the fire was just too strong.”
Police recovered the charred bodies of five people who had been travelling in a van. The burnt remains of two elderly women and an elderly man were found in a passenger vehicle. A 50-year-old truck driver also died. Police reportedly suspended rescue efforts at one stage, over concerns that the tunnel remained unstable and prone to further collapses.
The incident is the worst tunnel failure since 1996, when falling rocks and boulders, and a tunnel collapse in northern Japan claimed 20 lives.
The cause of Sunday’s disaster has yet to be established. Some experts have speculated that earthquakes and landslides may have contributed to the collapse. Police are reportedly investigating possible negligence on the part of the Central Nippon Expressway Company (NEXCO-Central), the firm operating the motorway.
NEXCO-Central claims to have carried out routine safety checks of the tunnel in September, but detected no problems. However, Ryoichi Yoshikawa, NEXCO-Central’s executive officer, told a press conference that the safety check did not involve physical testing.
Yoshikawa also indicated that the collapse might have been a result of ageing and poorly maintained infrastructure. “There were parts of concrete (slabs) where bolts had fallen off… The ageing of the bolts or the concrete slabs could be a potential cause,” he said. The company has confirmed that it had not replaced, reinforced or repaired the bolts since the tunnel was constructed in 1977.
At a press conference on Monday, a company spokesman acknowledged: “There was no record that we have conducted the tapping inspection at top of the ceiling in the tunnel.” He was referring to a procedure known as a hammer test, conducted to measure the compressive strength of concrete.
NEXCO-Central’s annual report for 2011 commented that “although hammer tapping test is commonly carried out to investigate concrete structures, it takes enormous time and cost to conduct the test on all concrete structures we have.” The company claimed that it tested using infrared cameras, but it is not known whether such testing was conducted in the Sasago Tunnel in September, or previously.
Motohiro Takamisawa, chief of NEXCO’s Otsuki Safety Centre, told journalists at the scene of the disaster: “At this moment we’re presuming that the top anchor bolts have come loose.”
Chikaosa Tanimoto, professor emeritus of tunnel engineering at Osaka University, told NHK that the concrete panels which collapsed were suspended in the tunnel 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,” Tanimoto said.
An earthquake registering 4.9 on the Richter scale struck beneath Tokyo Bay, shaking central Japan, on November 24.
The tragedy has raised broader fears over safety in tunnels across Japan. The Sasago Tunnel, one of the country’s longest, is just one of a number that are ageing. According to the Japanese Ministry of Land, Infrastructure, Transport and Tourism, around a quarter of Japan’s 1,575 highway tunnels are more than 30 years old.
Toyo University professor Yuji Nemoto told Bloomberg.com: “This accident shouldn’t have happened. This symbolises that Japan’s infrastructure—roads, bridges, water and sewers—is ageing because investment was concentrated in the 1960s and 1970s. Something must be done about this swiftly.”
Japanese authorities have announced emergency safety inspections of other road tunnels across the country, including 49 managed by the government. On Monday, Cabinet Secretary Osamu Fujimura called for “massive investment” to ensure safety, and a review of Japan’s ageing infrastructure.
Prime Minister Yoshihiko Noda called for inspection and maintenance work in a blog posting, but criticised calls for greater investment in public infrastructure. A focus on maintenance “is completely different from continuing to spend increasing sums on building new roads and facilities under the pretty name of ‘strengthening the country’,” he said.
The tunnel collapse occurred during the campaign for the Japanese general election on December 16. Noda’s remarks are directed against the opposition Liberal Democratic Party (LDP), which has promised to boost spending on infrastructure by an unspecified amount. In June, LDP lawmakers submitted a bill to spend 15 trillion yen ($US180 billion) on public works over three years. Noda has criticised the election promise as “wasteful pork-barrelling” and is pledging to cut the country’s huge public debt.
NEXCO-Central was established in 2005, when Prime Minister Junichiro Koizumi’s government privatised the Japan Highway Public Corporation. The move was part of a broader agenda of privatisation pursued by the Koizumi government, which included selling off Japan’s postal service.
While many questions remain, it appears that lax safety practices and the cutting of maintenance costs to boost profits contributed to the tunnel collapse.