Dr. Hana Takhtfiroozeh's Dissertation

Hana TakhtfiroozehApproaches to Vulnerability Analysis for Discovering the Critical Routes in Roadway Networks 

All modes of transportation are vulnerable to disruptions caused by natural disasters and/or man-made events (e.g., accidents), which may have temporary or permanent consequences. Identifying crucial links where failure could have significant effects is an important component of transportation network vulnerability assessments, and the risk of such occurrences cannot be underestimated. The ability to recognize critical segments in a transportation network is essential for designing resilient networks and improving traffic conditions in scenarios like link failures, which can result in partial or full capacity reductions in the system. This study proposes two approaches for identifying critical links for both single and multiple link disruptions. New hybrid link ranking measures are proposed, and their accuracy are compared with the existing traffic-based measures. These new raking measures integrate aspects of traffic equilibrium and network topology. The numerical study revealed that three of the proposed measures generate valid findings while consuming much less computational power and time than full-scan analysis measures. At the second part of this research, an optimization model based on a game theory framework and a heuristic algorithm to solve it is described to cover various disruption possibilities other than single link failure. The proposed methodology is able to identify critical sets of links under different disruption scenarios including major and minor interruptions, non-intelligent and intelligent attackers, and effect of presenting defender. Results were evaluated with both full scan analysis techniques and hybrid ranking measures, and the comparison demonstrated that the proposed model and algorithm are reliable at identifying critical sets of links for random and specially targeted attacks based on the adversary's link selection in both partial and complete link closure scenarios, while significantly reducing computational complexity. The findings indicate that identifying critical sets of links is highly dependent on the adversary's inelegancy, the presence of defenders, and the disruption scenario. Furthermore, this research indicates that in disruptions of multiple links, simply combining the most critical single links significantly underestimates the network's vulnerability and there is a complex correlation between critical links.

Published peer-reviewed journal articles

Takhtfiroozeh, H., Golias, M., and Mishra, S. "Topological-Based Measures with Flow Attributes to Identify Critical Links in a Transportation Network." Transportation Research Record 2675.10 (2021): 863-875


Peer-reviewed conference papers

Takhtfiroozeh, H., Machado, A., Golias, M., Evangelos, K., Hourdos, J., and Mishra, S., Transportation Research Board 101th Annual Meeting Transportation Research Board, "Identifying Critical and Vulnerable Freight Routes in the State of Florida"