Abstract
In this article, perspectives of prevention are discussed for accident and trouble in social infrastructure. Based on case-studies, a “dilemma in ignorance” will be focused. It means that an uncertainty of requirement for design, and represents an important issue in an achievement of high reliability and safety of system operations. Especially, for the social infrastructures, because of requirements of long time use, the uncertainties in demand and situation for use tends to be increased with years. Entry of various experts in the design review is required for an appropriate change control. In addition, the multiple faults, which is caused by the simultaneous occurrence of factors, should be predicted and considered with increased efforts.
