A broken axle led to the May 5 derailment of a roller coaster at the Expoland amusement park in Suita, Osaka Prefecture, which killed a woman and injured 19 other holidaymakers. Not only had there been a lack of safety consciousness on the part of the operator but also unclear legal stipulations concerning safety checks.

The operator, Expoland, usually disassembles roller coasters in January or February and uses ultrasonic and magnetic-wave devices to check for cracks in vehicle components. But this year, it postponed the regular checkup until May 15 or later — after Golden Week — on the grounds that no space was available for the procedure. With the large turnout expected during Golden Week, the operator’s decision was untenable.

The axle, 40 cm long and about 5 cm in diameter, broke almost perpendicularly. The surfaces of the broken sections are almost flat, indicating the possibility of metal fatigue. The company had not changed the axle since first putting it to use in March 1992. Nor was the company aware of the axle’s life span.

The operator’s failure to change the axle should be attributed to the fact that safety standards do not provide for regular replacement of components used in amusement park equipment. The Building Standards Law only calls for annual checks of roller coasters. Elevators are subjected to similar checkups. Operators virtually decide on the method and content of the checkups. Local governments only receive reports from operators; their officials do not conduct on-site verifications.

Although Japanese Industrial Standards call for checking a roller-coaster axle with ultrasonic and magnetic-wave devices at least once a year, the failure to observe the JIS stipulation does not necessarily constitute a legal violation. It is welcome that the transport ministry has decided to set down concrete procedures for checking amusement park equipment as well as make clear the relationship between JIS and other legal provisions. It is hoped that unmistakably clear safety-check rules will be worked out as soon as possible.

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