This thesis concerns research into the parametric modelling and optimization of steel-concrete bridge typologies typically found in the Netherlands, in order to further the automation of preliminary bridge designs. The research question posed is: "How can a parametric bridge design model be composed to fit into the
overall road design process in order to get a comparative overview of structurally sound bridge designs of different typologies?". Within the literature review some background information is provided about the design of steel-concrete bridges, parametric design, finite element modelling and evolutionary solvers for optimization. With this information seven different bridges are designed according to boundary conditions and requirements posed in a fictitious case. These bridge designs cover the beam-, truss-, arch- and cable stayed
bridge typologies. The designs are then parametrically modelled and converted to a finite element model in a single parametric design environment, after which they are structurally analysed and optimized for minimum costs. The result is that, for the fictitious case considered, the Warren truss without verticals is the
solution with the lowest costs. This bridge design is able to carry the loads, according to load model 1 from the Euro Codes,with a lower amount of structural steel compared to the girder beam bridges, and the absence of expensive cables in the structure makes it less expensive than the arch and cable stayed bridges. Due to the scope defined at the start of the research, there are some limitations. The costs calculated for the bridges are purely based on the bridge structure itself, foundations and approach structures are not considered and this has to be kept in mind when comparing the bridges. Finally, the research into how to implement this design and optimization tool into the overall design process has not been performed, however, the model is composed in such a way that it will be compatible with minor changes to the start and end of the process.