Japanese police have raided a highway company in a probe over the weekend's deadly tunnel collapse. Emergency workers retrieved nine bodies on Sunday.
Footage showed a dozen officers entering the NEXCO headquarters, seeking the company's safety records.
"We are fully cooperating with the authorities over the accident," a NEXCO spokesman said.
When the Sasago tunnel collapsed Sunday, concrete panels crushed three vehicles. One caught fire and filled the tunnel with smoke.
Crumbling with time
Media reported that investigators will likely ask NEXCO employees about potential negligence that may have led to the nine deaths, but police have made no arrests. Authorities also raided the company's offices in Tokyo and Yamanashi.
Officers launched an investigation into the tunnel itself, 80 kilometers (50 miles) outside of Tokyo. The commission to investigate such accidents also had plans to tour the 5-kilometer tunnel Tuesday, officials said. The government also dispatched inspectors to 49 such structures to check for decaying supports, considered a potential cause of the accident.
NEXCO's inspections often consist of acoustic and visual surveys, with workers hunting cracks and abnormalities in metal and concrete. Company officials said that September's five-year ceiling check had left out the acoustic survey of metal to support the concrete panels, each of which weighs over a ton and a half.
The company has yet to announce when the tunnel might reopen. About 47,000 cars use the highway each day. Traffic has since clogged bypass roads, according to media, which also reported interrupted flow of gods between Tokyo and western Japan since the accident.
Experts warn that Japan's structures have seen increasing decay with age and may require maintenance or replacement. Japan's highways have more than 1,500 tunnels through the country's many mountains. About 25 percent are older than 30 years, the Transport Ministry has announced.
Japan sees its share of earthquakes, and even after 20 years of increasing safety regulations, these post a risk to older structures, experts warn. In the 1960s and '70s, Japan saw a boom in constructing tunnels, bridges and other public works.
mkg/msh (AFP, AP)