A comprehensive survey of masonry bridge assessment methods: past to present

Masonry bridges, integral to transportation networks for over a century, have continuously adapted to evolving traffic demands and speeds, despite their original design catering to lighter loads and slower traffic. However, the prolonged exposure to diverse dynamic loads such as traffic, seismic events, wind, waves, blasts, and weathering, compounded by various environmental factors, has led to structural deterioration, presenting significant functional challenges. Identifying appropriate techniques for analysis is paramount for determining the life expectancy of these historic structures, ensuring their durability, and preserving their heritage significance. Regrettably, established protocols or codebooks for conducting assessments are lacking in many regions. The assessment of masonry bridges has evolved from initial reliance on empirical methods to the utilization of equilibrium methods, numerical analyses, and vibration-based approaches, facilitating a deeper understanding of their behaviour. Moreover, the implementation of Artificial Intelligence for assessment has gained global popularity due to its simplicity and robustness, particularly in evaluating both visual and material damage. This review paper comprehensively examines the most commonly used assessment methods, providing detailed insights into their strengths and weaknesses. Furthermore, it aims to disseminate information about recent advancements in assessment methods to both researchers and practitioners. These advancements are essential not only for laboratory-scale model testing but also for their practical implementation in real-time scenarios. Moreover, this study proposes the most appropriate method for a specific bridge considering factors such as timeline, geometry, and material characteristics. Ultimately, ensuring the long-term viability of these historic structures necessitates understanding appropriate assessment techniques and making well-informed decisions regarding conservation and strengthening measures.