Japan’s Board of Audit watchdog is probing whether West Japan Railways (JR West) Co. thoroughly tested its tunnels on the Sanyo Shinkansen (bullet train) line after a series of incidents of spalling concrete that have happened since June 1999.
The board is also considering similar action against East Japan Railway Co. (JR East), where similar problems have occurred.
The probe, which has been prompted by safety concerns from passengers, will look at the way JR West tested and discovered 41 000 weak spots in 142 tunnels along the Sanyo Shinkansen line between Osaka and Fukuoka.
The investigation will also focus on subsequent repair work by contractors, especially the way contracts were awarded.
The audit enquiry is the latest set-back for the rail company that operates bullet train services in western Japan.
JR West is set to spend $93m on tunnel repairs on the Sanyo Shinkansen line alone up to the end of March. This is considerably more than $18.5m it spent up to March 1999 before the falling concrete incidents occurred.The rail company admits that it has no idea how much repairs could cost.
JR West president Shojiro Nanya said: "We don’t have a definite picture of the financial burden this will incur on us but I’m sure we will be able to pay for this with our own funds."
He said that the company was also taking legal advice on whether to sue any or all of the 30 contractors which built the tunnels in the 1970s.
The tunnel problems have been largely caused by cold joints – where new concrete was laid on top of concrete that had already been allowed to cure.
Nanya also blamed contractors for using unwashed marine sand during construction, a period that coincided with acute materials shortages.
