Algorithm for estimating the construction year of Brazilian bridges between 1950 and 1980

Abstract The year of construction is an essential factor in assessing the condition of bridges, as it directly influences the prediction of their deterioration and the analysis of their load-bearing capacity over time. In addition, this data is fundamental for algorithms that deal with missing information, such as that related to design standards. This study proposes and validates an algorithm to estimate the year of construction of Brazilian bridges based on three main characteristics: design vehicle, barrier type and width. The aim of the algorithm is to fill this information gap and provide managers with information to manage these infrastructures. An analysis of 5,000 bridges in the Bridge Management System revealed that 41.7% of them had no record of the year of construction. During validation, the algorithm showed robust performance, achieving a hit rate of 87.82 percent and a mean absolute error (MAE) of 5.20 years. After adjustments, the MAE was reduced to 4.45 years, with accuracy rates of 99.46% (±10 years) and 79.62% (±5 years). In practice, the algorithm successfully estimated the year of construction in 81.87% of cases, with the majority of bridges built in the 1970s (64.16%). These results provide a solid basis for more accurate deterioration predictions and more reliable load capacity assessments, contributing to more efficient and safer bridge management.