AbstractThe sandwich plate system (SPS) is a structural composite material made up of two metal plates bonded to a polyurethane elastomer core. SPS delivers high strength and stiffness, making it an excellent alternative to conventional stiffened steel and reinforced concrete. For strengthening of orthotropic bridge decks, SPS Overlay can be used to create a stiff bridge deck without removing the original plates. The renewed deck improves the distribution of wheel loads across the longitudinal stiffening elements, decreases deck curvatures associated with large concentrated wheel loads, extends the fatigue life of fatigue‐critical welds and increases the life of the wearing surface and the whole bridge. For new bridge applications, prefabricated SPS bridge deck plates reduce the dead load by up to 70 % compared with concrete bridge decks, thus allowing bridges to carry significantly greater live load without the need for girder or pier strengthening. Deck replacement can be completed while leaving the steel or concrete girders in place or, where speed of erection is critical, pre‐assembled longitudinal deck‐girder units can be used.