INFLUENCE OF PEDESTRIAN FLOW INTENSITY ON THE STRUCTURAL DEGRADATION OF METALLIC PEDESTRIAN OVERPASSES: A COMPREHENSIVE STATISTICAL ANALYSIS IN LUANDA, ANGOLA

Urban pedestrian infrastructure in rapidly growing African cities faces increasing challenges associated with intensive use, environmental exposure, and insufficient maintenance. This study investigates the influence of pedestrian flow on the structural degradation of 31 metallic pedestrian overpasses along Deolinda Rodrigues Avenue in Luanda, Angola. A mixed-methods approach combined systematic visual inspections, photographic documentation, liquid penetrant testing of welded joints, and quantitative pedestrian flow analysis. Descriptive statistics identified corrosion (100% prevalence, mean severity 20.9%), surface wear (22.3%), paint degradation (23.9%), and cracking (14.9%) as the most common deterioration mechanisms. Spearman correlation analysis revealed significant positive relationships between pedestrian flow and all pathology types, with surface wear showing the strongest association (ρ = 0.455, p = 0.010). Multiple linear regression demonstrated that structural age was the main predictor of overall degradation (R² = 0.750, adjusted R² = 0.733, p < 0.001), while pedestrian flow provided a significant additional contribution. One-way ANOVA indicated significant differences in degradation severity among construction periods (F(3,27) = 29.51, p < 0.001, η² = 0.766), supported by Tukey, Mann-Whitney, and Kruskal-Wallis tests (p < 0.05). Effect size analysis showed a very large difference between the oldest and newest overpasses (Cohen's d = 5.04). Liquid penetrant testing revealed that all Type A overpasses failed acceptance criteria, whereas all Type C structures complied. These findings confirm that structural age is the principal driver of deterioration, while pedestrian flow significantly accelerates degradation, particularly mechanically induced damage, providing a robust basis for maintenance prioritization, predictive deterioration modelling, and infrastructure management in rapidly urbanizing sub-Saharan African cities.