Reconstruction of the railway bridge over the Stura di Ovada Stream at km 39+443 of the Genova–Ovada railway line.

Project objective

The Project provided for the reconstruction of the railway bridge over the Stura Stream, consisting of a steel girder span supported on two masonry abutments, with a clear span of approximately 60 m and an elevation above the riverbed of about 8 m. Railway traffic was kept in operation throughout the works.

Project description

For execution of the works, transverse launching of the new steel girder, replacing the existing one, was envisaged by constructing two temporary bridges alongside the existing bridge, one upstream and one downstream: the new structure was assembled on one of the temporary bridges, while the old structure was shifted onto the other for subsequent removal; therefore, launching was performed transversely.
To enable execution of the works, our Company designed and studied in detail all construction stages, in particular with reference to hydraulic risk conditions.
The abutments were built in reinforced concrete; the temporary piers were demolished at completion of the works and new bank protection works were constructed.
In the hydraulic study of the stream reach affected by the crossing work, the hydraulic compatibility of the existing structure and of the new structure under design was analysed in depth, as well as the potential occurrence of flooding phenomena that could jeopardise the stability of the bridge or of the existing railway embankment.
Steady-flow conditions were also verified, including possible effects in terms of water levels and safety freeboards, during the launching phases when the temporary structures were in place.
In the stream reach under consideration, slightly upstream of the railway bridge, two bridges of the Alessandria–Voltri motorway are present, one per direction of travel; these were considered in the study to assess possible mutual interferences and related effects on the steady-flow water-surface profiles.