The Dutch motorways are under pressure due to increasing traffic intensity, ageing infrastructure, and limited physical space (Rijkswaterstaat, 2025). These issues, particularly at interchanges, lead to challenges in creating safe and future-proof designs. In this study, the development of a redesign for the Harmsenknoop interchange was used to explore how design concessions influence traffic safety and flow. Concessions are defined as modifications to the ideal design that are necessary to make it spatially feasible, such as reducing the curve radius or lowering the design speed.