ABSTRACT
Bridges on heavy haul freight lines are subjected to significantly high loads arising from the need to increase haulage volumes through bigger wagons with high axle loads and high traffic volumes. The increase in loads has the potential to reduce the safety level of bridges as well as their service life. Bridge structural safety evaluation loads based on live loads from weigh-in-motion systems are developed for single span and two span continuous short to medium span bridges. The static load effects of moments and shear for 50years and 100 years are evaluated and compared with the load effects obtained from South African Bridge Railway Services design loads to obtain a safety factor of 1.15. Despite the increases in axle loads from 26 tonnes to 30 tonnes per axle on South African Iron Ore line, the static live loads obtained from design loading code are shown to be overly conservative for structural assessment purposes.
