The Carola Bridge collapse in Dresden

The collapse of the Carola Bridge in Dresden on September 11, 2024, represents a pivotal case study in understanding the failure mechanisms of aging post-tensioned concrete infrastructure. Constructed in 1971, the bridge was subjected to progressive structural degradation resulting from long-term environmental exposure, chloride ingress, fatigue loading, and insufficient maintenance interventions. These factors, in combination, culminated in a sudden and dramatic failure that highlights broader challenges in managing critical transportation assets.Comprehensive forensic investigations, structural analyses, fatigue and durability assessments, and expert interviews identified hydrogen-induced Stress Corrosion Cracking (SCC) of the prestressing tendons, particularly near pier D, as the primary cause of the collapse. This was aggravated by chloride-induced reinforcement corrosion and long-term cyclic traffic loads. Structural assessment showed that the bridge´s ultimate (ULS) and serviceability (SLS) flexural capacities were approximately 13-15% below modern Eurocode 2 requirements, revealing a significant loss of structural redundancy.Non-Destructive Testing (NDT) techniques, including Acoustic Emission (AE) and Ultrasonic Testing (UT), confirmed the presence of hidden tendon degradation that had not been captured by conventional inspection protocols. Additionally, deterioration mechanisms such as carbonation and freeze-thaw cycles further undermined the bridge´s performance.Expert insights from Professor Steffen Marx and Professor Manfred Curbach stressed the urgent need for integrating real-time Structural Health Monitoring (SHM), calibrated Finite Element Modelling (FEM), and proactive retrofitting to manage risks associated with aging infrastructure. Fatigue mechanisms, while secondary, played a contributory role in the accelerated decline of the bridge when interacting with environmental stressors.This study underscores the necessity of transitioning from conventional inspection routines to durability-based reassessments that integrate fatigue considerations, advanced diagnostics, and life-cycle management. The Carola Bridge collapse serves as a critical reference point for future strategies aimed at enhancing the safety, resilience, and longevity of prestressed concrete bridges.