Laura Schwab, Beat Hintermann, Alexander Goetz, Joseph Molloy (2026). Reducing transport externalities through nudging: Results from a GPS-tracked experiment
Published online in Journal of Environmental Economics and Management

Abstract
This study presents results from a randomized controlled trial in Switzerland that investigates the effects of a non-monetary intervention on transport choices. A GPS-based tracking app records the movements of 814 participants for several months, and automatically detects their travel modes. The treatment consists of sending personalized transport reports to a randomly selected subgroup. These reports contain personalized descriptive and prescriptive information on participants’ transport-related external costs. The treatment reduces the external costs of transport by 12.4%, but only on weekends, and only during the first half of the study. In the second half, the effect dissipates to zero. Based on participants’ travel responses and their willingness-to-pay for future reports, we estimate average gross welfare gains of 1.6–3.6 Swiss francs per participant per week in the short run. Of this, 0.8–2.8 Swiss francs reflect the private value of the reports rather than the temporary behavioral change.

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