Ensuring accessibility to large-scale housing sites in the Netherlands is crucial due to the housing crisis, limited space and financial constraints. Poor transport- and spatial planning decisions can lead to congestion and restricted access, issues often overlooked in fragmented policy-making. To address this, policy integration is needed. However, integration between transport and spatial planning remains unimplemented, creating a gap. In a qualitative way, this research tried to answer the question: How can the relationship between transport planning and spatial planning in the Netherlands be strengthened?. Here, a new policy integration concept of manageability is found alongside the concepts of coordination, coherence, and cooperation found in literature. Regional decision-makers should prioritize coherence and manageability at the start of decision-making processes, with coordination and cooperation as foundational elements. Recommendations include exploring policy integration in related domains in the Netherlands, exploring specific policy integration concepts, or dual relationships within the four established policy integration models of this research.