Taxes, tolls and ZEV zones for climate: Synthesizing insights on effectiveness, efficiency, equity, acceptability and implementation

We explore the potential role of road pricing in achieving deep GHG mitigation targets, including cordon zones, fuel taxes, VKT fees, and ZEV zones. While most research focuses on a single policy criterion, our comprehensive framework seeks to synthesize insights on five criteria: effectiveness (GHG mitigation), efficiency, equity, political acceptability, and implementation process. Further, we address potential policy mix interactions, and identify critical gaps to guide future research. Although results vary by region, we offer some general findings. First, stringent road pricing can be effective for GHG mitigation in the short- and long-run, especially for passenger vehicles (less so for freight), while also playing a complementary role to vehicle efficiency regulations (mitigating rebound effects). Second, both equity and political acceptability can be improved by careful design of exemptions and usage of revenues – though the ideal design seems to vary considerably by region. Finally, the implementation process is highly important for acceptability, which should include stakeholder consultation, clear communication of benefits, potentially a demonstration and referendum phase, and ideally agreement among political parties. There is much less evidence for ZEV zones, which don't seem necessary for GHG mitigation, though offering ZEV exemptions for road pricing may be an effective design feature.