In Germany around a quarter of the existing railway bridges are made of steel. In the upcoming years many of these must be substituted. Not only on new stretches of tracks but also due to replacement a yearly construction volume of about 250 railway bridges may be expected. Compared to concrete bridges it can be observed that for the majority of small and medium span steel and composite bridges are not competitive in regard of construction costs. Further criteria considering the whole life-cycle of a bridge during the decision making process may provide more opportunities for steel and composite bridges. Thus an holistic assessment of steel and composite railway bridges is applied to three different bridge types. Therefore the durability of the bridge constructions is enlarged by developing and optimizing the critical fatigue details, which are determining the life time of the bridges. Within this paper the critical construction detail of bridge type A is picked out to show the prolonging effects of post-weld treatment.