Planning transport infrastructure is particularly difficult due to infrastructure’s long-lived nature, unpredictable technological progress and changing mobility trends in society. In complex systems facing major uncertainties, exploratory modelling can help define salient system characteristics and discover potential risks and opportunities by evaluating large ensembles of potential conditions during the planning process. This paper demonstrates how exploratory modelling can provide planning support for a federal highway from Dübendorf to Hinwil in Zürich, Switzerland. We model the future traffic flows at peak hours considering uncertainty in urban development, jobs distribution and future modal share. Current road infrastructure and further potential capacity expansions and reallocations are then tested on their robustness to provide adequate performance (in terms of travel delays) in multiple future scenarios. We use quantitative methods to identify the subset of scenarios representing risks and opportunities for the infrastructure system. The visualization of such subset of scenarios in uncertainty maps can help target interventions only when needed.