Green Infrastructure: The Effects of Urban Rail Transit on Air Quality

Abstract

The transportation sector is a major source of air pollution worldwide, yet little is known about the effects of transportation infrastructure on air quality. In this paper we measure the effects of one major type of transportation infrastructure -urban rail transit -on air quality. Our approach uses the sharp discontinuity in transit utilization on the opening day of a completely new rail transit system in Taipei, Taiwan to identify the air quality effects of rail transit infrastructure.Using hourly air quality data from Taiwan we have three central findings. First, we find that the opening of the Metro reduced air pollution from one key tailpipe pollutant, carbon monoxide, by 5 to 15 percent. Second, we find little evidence that the opening of the Metro affected ground level ozone pollution. Third, we find little evidence suggesting that automobile travelers adjusted their time or route of travel to the availability of rail transit. These findings shed new light on the determinants of air quality, and suggest that environmental impacts are important components of the social value of transportation infrastructure.

On the Performance of the U.S. Transportation System: Caution Ahead

“…Winston and Shirley (1998) found that policies to induce those shifts were not effective because transit also produces pollution and operates with a low load factor and small mode share. Chen and Whalley (2012) used the opening of a new metro station in Taipei as an exogenous event to estimate the effect of urban rail transit on air quality and found that it reduced one key tailpipe pollutant, carbon monoxide, 5-15 percent, but it had no effect on ground level ozone pollution.…”

Meeting Asia's Infrastructure Needs

“…Yoshino and Abidhadjaev (2015) provide some evidence that a newly built railway in south Uzbekistan may have caused 0.4%~2.0% GDP growth in the regions affected. Finally, Chen and Whalley (2012) show that the opening of the new rail transit system in Taipei,China reduced air pollution from carbon monoxide, a key tailpipe pollutant, by 5%-15%. The results highlight the importance of urban public railway transit infrastructure.…”

The Effects of Urban Public Transit Investment on Traffic Congestion and Air Quality

“…Two recent studies have provided an initial look at the relationship between transit supply and air quality. Using hourly air quality data from Taipei [31], find that the new rail system's opening reduced carbon monoxide by 5-15% but had little effect on ground level ozone pollution [4,31]. In their analysis of the environmental effect of expanded rail service in Germany over the period 1994-2004 [32], find that increases in rail service frequency lead to a reduction in some pollutants (NO, NO 2 , and CO), though not others (SO 2 and O 3 ) [4,32].…”