Frequency of Railway Bridge Damage

Abstract

Bridge damage frequencies observed on a 5,500 mile (8,800 km) segment of railroad during a 10‐yr period indicate that the probability of damage is strongly influenced by bridge type and moderately influenced by location and traffic density over the bridge. Sixty‐eight incidents of serious damage were caused by high or shifted loads, fires, floods, collisions and derailments. The risk of fire damage to timber trestles is greater for open‐deck than for ballasteddeck trestles and increases with trestle length. The overall annual probability of serious damage was 0.0016. The annual probability of mechanical damage from derailments was 0.00019. That of high load damage to underpasses was 0.010. For shifted load damage to through trusses, without regard to traffic density, it was 0.030. It was 0.00027 for highwater damage to timber trestles and 0.00036 for fire damage to timber trestles of all lengths. The overall lifetime probability of damage in the order of 0.1, for an assumed 75‐yr life, appears to be an appropriate lifetime probability for serviceability failures.