OSAKA -- The crack found in the undercarriage of a Japanese shinkansen train in December likely was caused by a production problem that weakened the frame to a dangerous degree, manufacturer Kawasaki Heavy Industries said Wednesday.
Kawasaki Heavy and West Japan Railway, the operator of the bullet train in question, reported that an area of the steel frame had been ground below the 7mm standard in order to weld on another part. The steel was shaved to just 4.7mm at the thinnest point when the frame was made in 2007.
