Development of an orthotropic composite slab system for road bridges. Large increases in traffic loads lead to extensive fatigue damage to existing orthotropic steel deck slabs of road bridges. Reinforced concrete bridges and conventional composite bridges are less susceptible to fatigue, but considerably heavier. The so-called ortho-composite slab is a comparatively lightweight and robust alternative construction method, which retains the advantages of the previously mentioned construction methods, but eliminates their disadvantages. Within the framework of the AiF-FOSTA research project P 1265, the construction of the bridge deck is being developed using dowel strips as composite elements with high load-bearing capacity and fatigue resistance. The principle of area composite with loading of the dowel strips in longitudinal and transverse direction is used. Extensive experimental and structural-mechanical investigations were carried out, with which in particular the load-bearing capacity and fatigue strength of the ortho-composite slab under local load transfer and of the dowel strips under loading and transverse direction were investigated. The following article describes the motivation for the research project and gives an overview of the investigations carried out. In addition, a pilot project is presented that was carried out for the application of the construction method.