The Yomiuri Shimbun The latest case of inappropriate work on Shinkansen part reveals a heavy responsibility for hindering safe transportation by deviating from the proper manufacturing process.
West Japan Railway Co. has released investigation results regarding the case in which there was a crack in the undercarriage frame of an operating Nozomi Shinkansen train, which could have immediately led to a rupture. The crack resulted from the fact that Kawasaki Heavy Industries, Ltd., the manufacturer of the frame, had inappropriately scraped its undersurface.
The frame in question was produced in 2007. Although the steel used for the frame needed to be at least seven millimeters thick, it was only 4.7 millimeters thick at its thinnest section. This led to a lack of sufficient strength, allowing a small crevice in a welded part to widen.
The undersurface of the frame was scraped to tightly weld components to it. According to Kawasaki Heavy’s in-house regulations, scraping undercarriage frames was banned in principle, except that sections around their welded parts were allowed to be scraped by up to 0.5 millimeters.
An on-site supervisor mistook this rule and instructed that the whole undersurface of the frame should be scraped. As the thickness of steel materials was not included in the list of items to be examined at an inspection of finished products, the fault in question was overlooked. Both were serious errors.
Undercarriages are important parts that support the high-speed operation of Shinkansen trains. The Japan Transport Safety Board has acknowledged the latest case as a “serious incident,” marking the first for a Shinkansen-related problem to be treated as such. This reflects none other than a strong sense of urgency that the situation could have developed into a severe accident.
JR West must share blame
Kawasaki Heavy President Yoshinori Kanehana apologized at a press conference, saying, “Although [the company] has continued quality-first production, we are reflecting [on the latest incident] very seriously.” Kawasaki Heavy must be described as lacking a sense of responsibility as a train car manufacturer regarding its duty to protect the safety of passengers.
Kawasaki Heavy must drastically reconsider its corporate structure, including communication between its administrative division and on-site workers, as well as how its quality control should be conducted. The Land, Infrastructure, Transport and Tourism Ministry should also closely inspect the sequence of circumstances that led to the latest case, and consider preventive measures helpful for other makers.
JR West and Central Japan Railway Co. were supplied with a combined total of 147 Kawasaki Heavy undercarriages whose steel materials lacked sufficient thickness. Although replacement work has started for some, it is said it will take time for the work to be finished for all.
Replacement work should be advanced as quickly as possible. If undercarriages whose steel materials are yet to be replaced continue to be used in Shinkansen operations, thorough measures must be taken to confirm their safety through ultrasonic testing and other methods.
JR West Vice President Yoshihisa Hirano criticized Kawasaki Heavy, saying, “It’s obvious that the strength [of steel materials] cannot be maintained if they are scraped. Doing so was work that must not be done.”
However, JR West cannot be absolved from responsibility in this respect. The company continued to operate the Shinkansen train for as long as about three hours, despite a foul smell and an unusual sound being noticed. That may have allowed the crack to come close to a rupture.
JR West has released preventive steps, such as a maintenance worker immediately going aboard a train if there is an abnormal occurrence. It is important to be sensitive to any abnormalities on a train and to halt the operation of the train without hesitation.