Keywords: steel bridge, fatigue, traffic volume, history.

More and more railway steel bridges are near the end of their lifetime and are affected by material fatigue. To optimize the maintenance cost plans, fatigue life assessment can be updated using estimates of traffic development of bridge’s lifetime. A concept for adjusting fatigue traffic load models with respect to past traffic data was created. It provides a rough estimate of traffic volume development from the point-of-view of bridge fatigue. The method uses the relative change of network-aggregated traffic volumes of the past in relation to the present. The data for the past is either directly available from country’s statistics, or it can be estimated from country’s macroeconomic indicators. The relation between traffic volume and macroeconomic indicators was established using simple linear regression, applied separately on data of each country. The estimates derived from macroeconomic indicators require plausibility check and are generally less reliable. The estimated history of traffic volume development is then used to update the number of train passages of all train types in the traffic model for the past years. Of course, the estimates depend on the assumptions that the distribution of country’s rail traffic to different routes is uniform and that the past wagon material and its load utilization is same as present. This approach provides rough estimates and is open to inclusion of more accurate data, such history of regional (section-specific) traffic volumes, which may differ from the network-aggregates. The proposed method was implemented with the aim to get an improvement of knowledge level of fatigue consumptions and to provide a better basis for improvement of life-cycle analysis of steel bridges, and therefore help to renew these bridges in a more economic way.

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