The existing stock of road and railway bridges in Italy and in most European countries frequently
exhibits insufficient performances, both in terms of structural safety and functionality, compared to
the current demands coming from modern structural codes, transportation systems and necessity of reducing
the costs of maintenance. Quick and reliable methodologies are then needed to assess the specific vulnerability
of any bridge typology, in any possible environmental and operating conditions. In the first part of the paper
the application of such type of methodologies to both road and railway transportation infrastructure in Italy
is described showing that, e.g., masonry arch bridges are usually quite robust structural systems, r.c.
bridges generally present durability problems and are vulnerable to seismic actions, steel bridges, other than
presenting durability problems, are particularly vulnerable to fatigue. Typical retrofitting interventions considered
in these studies are also briefly presented. In the second part of the work significant case studies of retrofitting
interventions are in more detail described, focusing on four existing r.c. bridges, which represent an
homogeneous set, all of them being part of the post-IInd World War reconstruction on the Adige River (the
second longest river in Italy). These bridges are examples of some of the most usual typologies adopted in
that historic period, and the defects they evidenced after fifty years of service life were typical of these kind of
structures, being often the consequences of a poor maintenance and the lack of durability rules in the original
design. The refurbishment interventions are presented outlining a methodological approach, which takes into
account the typological characteristics of the structure, the state of maintenance, the functional requirements
and the environmental aspects connected to the repair and strengthening system.