The impact of social externality information on fostering sustainable travel mode choice: A behavioral experiment in Zhengzhou, China

Abstract

Urban leaders in areas with high air pollution often face the dual task of reducing pollution levels while educating the public about the health impacts of pollution and preventive measures. Transportation policies to cut motorized personal vehicle use are often a key part of pollution reduction efforts. One type of these policies is information interventions educating commuters of the higher emissions impact of cars. This study evaluates the impact of such an information intervention on car commuters’ intention to switch from car use to transit, biking, or walking in Zhengzhou, China. Further, it tracks how this greening impact evolves as drivers are given additional public health information regarding Zhengzhou’s severe air pollution level, its health effects, and the reduced pollution exposure when driving compared with transiting, biking, or walking outside in polluted air.

Using a randomized controlled survey experiment with a treatment group of 281 participants and a control group of 280 participants drawn from Zhengzhou workers who typically commute by car, this study applies multinomial logit models and difference-in-difference estimation to estimate the information intervention’s impact. We find that while emissions information interventions are initially highly effective in reducing intended car usage, the effect is progressively dampened as respondents learn of the level of local air pollution and the risks of outdoor pollution exposure. Some greening effects do, however, remain even at the end of the experiment. The results suggest that governments in polluted areas must be aware of how policies in different segments of their portfolio interact and support broader initiatives like mixed-use planning and transit extension, simultaneously cutting transportation emissions and creating shorter commute durations with lower outdoor pollution exposure.