The sustainable development of large transport infrastructure projects is vital to addressing societal challenges such as climate change, biodiversity loss, and urbanisation. In the Netherlands, the MIRT framework (Multi-Year Programme for Infrastructure, Spatial Planning and Transport) structures the planning and decision-making process for such projects. The exploration phase of the MIRT process is particularly critical, as it is where strategic ambitions are translated into project objectives at relatively low cost and high influence. Yet large transport infrastructure systems are complex socio-technical systems, which makes embedding sustainability in their early stages challenging. Complexities are not only caused by technical or innovative constraints, but primarily because of divergent stakeholder interests, organisational complexity, and financial and spatial limitations.
This research examines how sustainability is defined, debated, and embedded in MIRT explorations, and how the process can be structured to safeguard ambitions. It describes two case studies: Station Dordrecht and the Amsterdam–Haarlemmermeer (OVAH) connection. Using a combination of a literature review, document analysis and expert interviews the study traces how sustainability is operationalised in practice. The findings show that sustainability is a normative and context-dependent concept, interpreted differently across cases. Its definition and integration are strongly shaped by site-specific conditions, the scale on which the project makes impact, and the organisation of the process of embedding Sustainability. The study also identifies 24 influential factors across 10 themes that affect the successful integration of sustainability considerations.
Building on these insights, the research proposes a toolkit that reconceptualises sustainability in large transport infrastructure projects as an organising principle rather than a separate goal. The shift in perspective is based on three key insights: first, sustainability is inherently normative, shaped by the values and institutional contexts of the actors involved; second, the use of the label “sustainability” to refer only to a limited set of themes does not do justice to the multidimensional nature of the concept. This narrow framing can lead to misconceptions about what sustainability truly entails within a project context; and third, despite divergent interpretations of the concept, consensus and a converged understanding can be achieved when the process of embedding sustainability is approached in a structured and systematic way.
The toolkit translates these insights into practical guidance for embedding sustainability in governance structures, assessment frameworks, and decision-making processes. By organising the MIRT exploration itself as a sustainable process, projects can anchor sustainability within project logic and ensure it becomes an integral and lasting component of Dutch infrastructure planning.