Reducing traffic with “carrots”: A review of the evidence
本文综述了非强制性政策（如改善公共交通、改变城市形态、提供信息等）对减少全国道路车流量的实证证据，发现这些措施对总体车流量影响很小，尤其难以满足快速大幅减排的气候目标。
Reducing traffic volumes is one way to reduce carbon emissions from the transport sector. Since increasing driving costs is often met with public resistance, high hopes are often pinned on the possibility to reduce traffic volumes by non-coercive policy measures, or “carrots”. Such measures include improvements of alternative modes, strategies that affect urban forms, and “soft measures” that aim to affect behaviour by providing information or changing norms and attitudes. This paper reviews the empirical evidence regarding such measures, focusing on their potential to reduce aggregate road traffic volumes in a national perspective. While such measures can yield significant other benefits, and may also reduce traffic volumes locally, our general conclusion is that their effects on aggregate traffic volumes appear small, especially from a climate policy perspective where emissions need to be cut radically and rapidly. While they are often motivated for several other reasons, overestimating their effects on aggregate traffic volumes may cause complacency, misallocations of scarce public resources and backlashes against climate policy.