A series of dynamic tests, acceleration measurements, evaluation, finite element model simulations and safety index calculations were performed on existing steel railway bridges giving service on railway network. Dynamic tests were fulfilled by using a special test train on these bridges to obtain the dynamic parameters and these parameters were then used to refine the finite element models of the bridges. Once the models have been updated to represent the actual condition, safety indices were calculated for structural components of the bridges for each proposed loading condition. These safety indices were used to calculate failure probabilities of structural members. As the final step, system reliability of the bridges was evaluated based on proposed system models of the bridges. It is believed that this study will provide a reliable background for proposed heavier axle loads resulting from new freight trains by realizing the current condition of bridge structures. (C) 2011 Elsevier Ltd. All rights reserved.