Bridges security risk assessment considering uncertainty in network topology

The proposed models to assess the security risks of bridges are generally designed based on the product of three-factor: probability (O), vulnerability (V), and importance (I). In this paper, the importance of bridge (I) and its changes due to the uncertainty of network topology during future network development programs were discussed. To measure and compare the relative importance of bridges, two groups of unique importance and the network-based importance of bridges were considered. Given that the network-based characteristics of bridges change during network development, a numerical example was presented to compare different decision-making approaches in selecting bridges (with and without considering the changes in the importance of bridge networks due to network changes). In this example, the Ahwaz inter-city transportation network was examined. The results showed that some bridges, such as B3, which were not important in the initial, became important during the development process. In contrast, in some bridges, such as B5, the relative importance was high at first, but during the development process, their relative importance decreased. It was also observed that a number of bridges such as B1, B6, and B7 are always important. In contrast, bridges such as B4 are always considered insignificant and network changes do not place them among the important bridges in any period.