The so called Steyrthal Bridge is situated in the Phyrn area of Upperaustria. It is a steel bridge with three single spans of approximately 30 m, 80 m and again 30 m. In addition it has two arches build as natural stone masonry both at the beginning and at the end of the structure. The so called Brunngraben Bridge, a single span steel bridge, is situated in the middle Ennsvalley in Upperstyria.
Both bridges are railway bridges and are part of the Austrian railway network, to be more precise of the railway line Linz – Selzthal. Due to problems with the load bearing capacity when the track classification of the named railway line is raised to class E in both cases a new building is obligatory.
Since the erection of both constructions must take place with active railway operation, quite special boundary conditions must be considered. For example these can be the adherence to the clearance beneath the superstructure or also the available period of stopped active railway operation.
For Steyrthal Bridge an additional special problem must be considered. The planned overall length of the Steyrthal Bridge will be approximately 185 m. The superstructure should be a continuous beam steel–concrete composite bridge with three gaps. In spite of the big total length of the superstructure no rail expansion joints should be used.
All these points were a quite special challenge for the planning. How this was solved with an extremely innovative construction for the Brunngraben Bridge and which lessons we have learnt with adoption of the Eurocode for the combined response of railway track and superstructure will be part of this paper.

bridge, Eurocode, combined response of structure and track, maintenance, execution class