The transport ministry will set up a panel to probe Sunday’s deadly collapse of a ceiling inside an aging highway tunnel west of Tokyo that may have not been properly maintained.
The panel will probably focus on beefing up regulations for managing and maintaining key road infrastructure, with an eye to creating a stricter inspection regimen and wider, more extensive and uniform safety checks.
The collapse, which took place in the Sasago Tunnel on the Chuo Expressway, which links the capital with major cities to the west, left nine people dead. The site is about 80 km west of Tokyo.
The suspended ceiling structure that collapsed is also used on toll roads with high traffic volumes in urban tunnels, according to the Ministry of Land, Infrastructure, Transport and Tourism.
They include the Haneda, Yamate and Asukayama tunnels, comprising six corridors, on the Metropolitan Expressway, or Shutoko, in Tokyo, and the Shin-Kobe and Kobe-Nagata tunnels on the Hanshin Expressway.
The ministry has ordered that they be inspected immediately ahead of the holiday period when traffic volumes are expected to rise. Four tunnels on the Shutoko faced inspection Tuesday and Wednesday, while those on the Hanshin Expressway are due to be checked by Friday.
Public attention is focused on whether the ministry can take the initiative in scrutinizing regulations and taking other steps to ensure safety.
An official at the ministry said “steps need to be taken” for toll road facilities that are aging. But the ministry says inspection and other maintenance activities remain under the purview of each highway operator as provided for by the special measures law on road maintenance that took effect in 1956.
The Chuo Expressway, for instance, is managed by Central Nippon Expressway Co. It is one of the regional companies established in 2005 after the breakup of Japan Highway Public Corp. and still entirely owned by the government.
Each company formulates its own manuals for tunnel inspections on toll roads according to the guidelines drawn up by the Japan Road Association, which groups highway operators.
The guidelines are based on the transport ministry’s technical standards issued in a 1989 notice, but the ministry says it is not involved in the inspections themselves.
Some bolts were found to have come off from fixtures supporting ceiling panels in Chuo Expressway tunnels, an official at CNEC said, but the company says it has no criteria to check if bolts are experiencing metal fatigue. It also said it has kept no written records of maintenance of the bolts and conducted no hammer tests to discover any potential abnormalities via this kind of acoustic check.
The association’s guidelines, however, do not list hammer tests as a required part of tunnel inspections, but only say “necessary points (for such tests) should be narrowed down through visual checks.” No provisions are set either on the desired frequency of maintenance.
CNEC thus argues its apparent inaction regarding the bolts does not go against the guidelines.