Grappling with uncertainty in the long-term development of infrastructure systems

Infrastructure systems are crucial to the functioning of society. Their long-term planning is therefore of great importance. Uncertainty about the future conditions under which an infrastructure system will function is of particular importance for successful long-term planning. The uncertainties about the future encountered in the long term planning of infrastructure systems is increasing due to developments such as privatization, liberalization, globalization, and climate change. Despite the increasing uncertainty, planning is still based on the outdated assumption that the future can be predicted accurately enough for static planning. We review the state of the art of an alternative planning paradigm that starts from the explicit recognition of the inability of forecasting and the need for adaptivity and flexibility. In light of the review, we present a research agenda identifying four areas of research: the methods and techniques employed for crafting adaptive policies, the institutional challenges for the successful implementation of adaptive policies, research into the efficacy of adaptive policies, and questions related to the assessment of the costs and benefits of adaptiveness.