Quantitative Risk Assessment of Road Networks Subject to Natural Hazards: A State-of-the-Art Review

Road networks are fundamental to economic prosperity and social cohesion through the efficient transportation of goods and people. Due to the increased number of natural hazards, it is essential to increase the resilience of road networks. Quantitative risk assessment is crucial to measure the extent of structural and functional damage to road networks after natural hazards. However, there is a lack of comprehensive reviews on quantitative risk assessment techniques. This paper conducts an exhaustive literature review, focusing on quantitative risk assessment of road networks subject to natural hazards, evaluating approximately 350 articles from peer-reviewed journals, conference proceedings, and technical reports. Five major natural hazards were considered: earthquake, flood, hurricane, tsunami, and landslide. The methodology consisted of five stages: searching articles using predefined keywords, screening articles based on their titles, checking the articles, selecting articles for inclusion, and analyzing them to categorize them into different sections. The categorization was done using following approaches—based on components used, developed performance metrics (e.g., risk, vulnerability, and resilience), methodologies, different life-cycle phases, fragility function development methods, risk assessment techniques using advanced methods and techniques, and consideration of socio-economic impact. The analysis indicates that recent studies predominantly focus on assessment techniques, with 90% emphasizing methodology and 10% tool development. Section 4 highlights that 85% of the studies delve into retrofitting, response, and recovery strategies. Earthquake and flood hazards are primary focal points in all sections, with tsunami hazards being notably scarce. This review provides a comprehensive synthesis of recent scholarly articles and insights into areas where extensive research is required.