Connectivities between processes in product developments indicate both conflicts of resources and potential synergies. These represent constraints and potential opportunities in planning design Each product development comprises a network of processes. Similarity between processes is analysed by a layered classification ranging from common components to shared design knowledge. The connectivities between products arising from similarities among products are represented by a multidimensional network. Design planning is described by flows or ‘traffic’ on this network which represents a structural model of complexity. Comparison is made with information based measures of the complexity of designs and processes.