A Fuzzy Approach for Assessing Transportation Infrastructure Security

The security of any transportation infrastructure can be defined as a combination of threat likelihood, infrastructure resilience, and consequence. In view of their inherently dynamic and highly unpredictable nature, threat likelihood and consequence data is difficult to determine with certainty. Due to this problem, this paper presents a new fuzzy methodology to qualitatively determine the overall security level, in terms of a security rating, for transportation infrastructure by duly considering the uncertainties of the environmental threats it faces, its resilience to damage, and the consequences of the infrastructure damage. The method is useful when data is unavailable or imprecise, allowing the security rating to be determined using a qualitative expert-assigned level that each factor contributes to overall security. The evaluation of the security factors are represented as fuzzy triangular numbers with accompanying membership rules that define the extent of contribution by each factor to overall infrastructure security. Through a case study, the paper applies the methodology to illustrate how general data can be used in the method to determine the overall security of specific infrastructure.