Cost overruns in Sweden’s transport infrastructure investments: evidence against the Planning Fallacy and the Hiding Hand

There is a dearth of evidence on whether Planning Fallacy or Hiding Hand explains cost overruns. We analysed all Swedish road and rail infrastructure investments finalized 1998–2025. 3% of roads and 6% of rail fit the Planning Fallacy narrative of failing both with respect to cost and benefits. 14% of road and 12% of rail projects fit the Hiding Hand narrative of going over budget but also delivering higher than planned net benefits. Many projects, 52% of roads and 40% of rail, fit neither the Planning Fallacy nor the Hiding Hand; they are, instead, successful. Overall, the results provide little support for the strong Planning Fallacy narrative and only limited support for the Hiding Hand, suggesting instead that most Swedish transport infrastructure projects perform broadly as expected when assessed against estimates at the final go-ahead decision.