Are We Successful in Reducing Vehicle Miles Traveled in Air Quality Nonattainment Areas?

摘要

An important planning and policy question in the transportation, energy, and environment areasis whether or not air quality control and the associated funding preference and mitigation effortsto attain air quality conformity have indeed led to traveler behavior changes such as reduction invehicle miles traveled (VMT) or VMT growth rates. In this research, we develop statisticalmodels to analyze the relationship between air quality nonattainment designation and VMTbetween 1966 and 2008 based on observed data. These models employ different statisticalmethods, including hypothesis testing, multiple regression, and simultaneous equations. Findingsfrom all statistical models and datasets are consistent, and suggest there is a statisticallysignificant negative correlation between nonattainment designation and VMT/VMT growth. Forinstance, the simultaneous equation model, arguably the most advanced model developed in thisresearch, suggests that if a nonattainment area and an attainment area that are similar in all otheraspects (population composition, socio-economics, urbanization, fuel price, vehicle stock, etc.)are compared, the VMT in the nonattainment area will be 1.75% less than that in the attainmentarea in the short run, and 7.34% less in the long run. When results from all models aresynthesized, the short-run VMT reduction effects of nonattainment designation range from1.13% to 1.75%, and the long-run effects range from 3.54% to 7.34%. While these results showstrong statistical evidence that efforts in reducing VMT in nonattainment areas have beensuccessful, future research should be conducted to attribute the VMT reduction effects to specificpolicy instruments for decision-making (e.g. the Congestion Management and Air QualityImprovement program, the conformity regulation in the transportation planning process, etc.).