This paper presents a novel approach to modelling and documenting design knowledge: to use parametric technology to explicitly store knowledge which exists in a group of people (such as a company), so that it can be reused over many projects and grow over time when more projects are designed. This approach has been applied and tested on a test case of common concrete viaducts. The outcome constitutes the first iteration of the development of a parametric viaduct design platform, aimed for architects and structural engineers. The motivation was to counter the fragmentation of the Architecture, Engineering & Construction (AEC) industry, where each discipline encapsulates different knowledge areas, which results in miscommunication and the loss of valuable information and time. The suggested methodology aims at combining the BIM principles [1] with the concepts of parametric and associative design, as well as visual programming [2] to develop a common design platform for the architect and the structural engineer. Such a platform ensures that both disciplines are working on the same design and merges their different knowledge areas into one model. The knowledge model evolves from a top-down UML diagram into a user-friendly, parametric platform for viaduct design implemented in Dynamo [3].