When dealing with the construction of a bridge or the assessment of an existing bridge to traffic loads, one important point is the prediction of reliability levels for critical details to the expected traffic loads in its remaining lifetime: this is done here for details of a steel-orthotropic bridge deck based on limited traffic monitoring data. A comparison of results from different statistical approaches is made by analyzing the recorded data for the traffic actions: to do that, the work begins with the writing of limit state functions for the ultimate limit state using various probability distributions, to evaluate the corresponding reliability indexes. Indeed, three methods to assess extreme values, Generalized Extreme Value, Peaks-over-Threshold and Level Crossing Counting, are applied. Therefore, one of the extrapolation methods that have been used in the background works for the European Norms (Eurocode 1) is treated here. Moreover, the comparison with the European design load model and the corresponding ultimate limit state is made.