Green Infrastructure: The Effects of Urban Rail Transit on Air Quality
نویسندگان
چکیده
Exposure to airborne pollution has substantial adverse health consequences. A recent World Health Organization (WHO) study has estimated that urban air pollution accounts for 6.4 million years of life lost worldwide annually (Cohen et al. 2004). Many harmful pollutants are emitted by automobiles. For example, Currie and Walker (2011) estimate that prenatal exposure to traffic congestion alone reduces welfare in the United States by $557 million per year. However, while the adverse health consequences of automobile pollution are widely acknowledged, little is known about the effects of transportation infrastructure on air pollution. In this paper, we ask whether the air quality effects of one major type of transportation infrastructure—urban rail transit—represent significant benefits. Conceptually, whether rail transit infrastructure has any meaningful effects on air quality is unclear. On the one hand, a rich theoretical literature following Mohring (1972) has argued that rail transit is subject to increasing returns to scale. Ridership increases engender higher service frequencies, reduce the average waiting times at stops, thus encouraging further ridership. The “Mohring Effect” implies that investments in rail transit infrastructure divert marginal automobile travelers away from
منابع مشابه
Green Infrastructure: The Effects of Urban Rail Transit on Air Quality Supplemental Appendix
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