An extradosed bridge employs a structure that combines the main elements of both a prestressed box girder bridge and a cable-stayed bridge. The name comes from the word extrados, the exterior or upper curve of an arch, and refers to how the "stay cables" on an extradosed bridge are not considered as such in the design, but are instead treated as external prestressing tendons deviating upward from the deck. In this concept, they remain part of (and define the upper limit of) the main bridge superstructure. Compared to a cable-stayed or cantilever-girder bridge of comparable span, an extradosed bridge uses much shorter stay-towers or pylons than the cable-stayed bridge, and a significantly shallower deck/girder structure than used on the girder bridge. This arrangement results in the typical extradosed "look" of a fan of low, shallow-angle stay cables, usually with a pronounced "open window" region extending from the sides of each tower. The extradosed bridge form is mostly suited to medium-length spans between and , and over fifty such bridges had been constructed around the world as of 2012. Whilst incurring many of the construction costs of both the cable-stayed and girder bridge types, extradosed bridges can deliver material savings to offset much of this penalty. They have frequently been adopted when overall height, navigation clearance, or aesthetic requirements have made the cable-stayed or girder alternatives less feasible. History The earliest bridge known to incorporate some of the features of an extradosed design is Bridge in Rzuchów near Leżajsk, constructed in Poland in 1980. Next is the Ganter Bridge, constructed in Switzerland, designed by Christian Menn of Zurich, it preceded by several years the 1988 publication on the design philosophy of such bridges by Jacques Mathivat, who is credited with inventing the extradosed terminology and its design concepts. The Ganter Bridge is a modified prestressed concrete cantilever girder design, where the longitudinal "continuity" tendons are raised significantly above the deck height at the ends of each main span and supported on short towers. These tendons are encased in fin-like blade walls on each side of the towers for protection, a design arrangement now often referred to as a cable-panel bridge. Whilst little is known of the origin of Menn's design, Mathivat developed a theoretical basis for such a concept during 1982-1983 while preparing a tender proposal for the Autoroute A64 viaduct across Arret-Darre in France. Mathivat's design replaced the internal tendons