A module of road safety barrier for contacting and redirecting an errant vehicle includes a first beam, a second beam, and uprights that support them. The first beam has a first longitudinal part projecting laterally with respect to the uprights and also has a second longitudinal part projecting laterally with respect to the uprights, on the opposite side of the uprights with respect to the first longitudinal part. The first longitudinal part and the second longitudinal part are each joined to both of the uprights by means of permanent joints and are joined to one another by welds or brazing so as to form an internally hollow beam with longitudinal slots. In manufacturing, the whole module is galvanized.