A methodology inherent to existing structures is presented for the fatigue safety verification of riveted bridges. The suggested approach allows for the determination of updated action effects explicitly considering data from long term monitoring. Data from monitoring allow for accurate determination of fatigue relevant stresses in fatigue prone bridge elements, and uncertainties in the determination of updated action effects are reduced. By means of the presented approach, the fatigue safety of a riveted railway bridge of high cultural heritage value was verified after 115 years of service duration. Data from monitoring were exploited by Rainflow analysis and served as the basis for the fatigue safety verification. As the locations of measurements are generally not identical with the cross sections of verification, measured strains were translated to the relevant verification cross section by means of factors that were determined by structural analysis. Sufficient fatigue safety was finally verified for the entire riveted structure and additional service duration of at least 50 years was validated.