The Sasago tunnel in Yamanashi Prefecture, where a fatal cave-in occurred on Dec 2 killing nine people, fully reopened on Friday afternoon.
After the accident in the inbound lane, the government ordered Central Nippon Expressway Co (NEXCO) to inspect the Sasago and other tunnels, especially ceiling panels. An inspection of the tunnel’s outbound lane revealed defects in 670 locations. The bolts which fix the ceiling panels to the nearly 5-kilometer-long tunnel were loose or corroded in about 632 places, TV Asahi reported. In other parts of the tunnel, the concrete top of the tunnel was cracked. In all, the company said it had detected problems in 670 spots.
NEXCO said its inspections consisted largely of visual surveys, with workers looking for cracks and other abnormalities, or listening to the acoustics of the concrete and metal parts by hitting them with hammers.
Officials admitted that during the five-yearly check of the ceiling, which took place last September, there had been no acoustic survey of the metal parts on which the panels weighing up to 1.5 tons rest.
A NEXCO official said Friday that all ceiling panels have been removed from the tunnel and said that fans have been installed for ventilation.