All bullet trains in Japan are being checked to identify any anomaly after the country suffered its first blip to its high-speed train safety track record in December last year when severe cracks were found on the bogie frames of one of the shinkansens, officials here said.
In the 54 years of its existence, there has been no fatality on the shinkansen system.
On December 11 last year, a 16-cm crack at the bottom of a steel frame holding the set of wheels and two 14-cm fissures on both sides of the frame were discovered by investigators who were probing a burning smell and an abnormal motor sound in a bullet train after it left Hakata station in Fukuoka, in southwestern Japan, for Tokyo.
Though none of the 1,000 passengers was injured, preserving Japan's record of zero casualties since the shinkansen started running in 1964, investigators said the cracks could have caused a derailment and used the label "serious incident" for the first time.
"We are conducting magnetic particle test in all our trains. We are checking the thickness of all our bogie frames as we have found that the frames in which the cracks appeared were thinner than the minimum required. If we find any frame to be thinner, we will replace it," Takano, assistant manager in-charge of the rolling stock at the JR Kyushu Railway Company, said.
Besides JR Kyushu, four other companies -- JR East, JR Central, JR West, and Hokkaido Railway Company -- operate bullet trains in Japan.
Similar checks are being conducted across all shinkansens, he said.
In February, Kawasaki Heavy Industries, the manufacturer of the shinkansen undercarriage on which the cracks were found, offered an apology over the incident and disclosed it had shaved the steel frame thinner than the minimum required for the boggies, a practice that violated the company's production manual.
The company said workers did not fully understand the document and they scraped off the bottom of the undercarriage frame to smooth the surface before welding work.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)