NCPA - National Center for Policy Analysis


September 28, 2007

Elected officials and policymakers frequently cite CO2 reductions as a reason to support light rail and reduce road surfaces.  However, any strategy to reduce CO2 that increases congestion is risky, costly and potentially counterproductive, says Todd Myers, Environmental Director with the Washington Policy Center. 

Using traffic and transit data provided by the WA Department of Transportation, Sound Transit and the Department of Ecology, the Center estimated the per-passenger CO2 emissions across I-90 in 2030.  There were three interesting results:

  • Light rail will reduce CO2 emissions by about 6 percent during the peak hours assuming that 30 percent of passengers crossing I-90 ride light rail as is projected by Sound Transit; if the percentage of passengers crossing I-90 falls to 22.5 percent, that daily savings disappears.
  • Most of the greenhouse gas emissions reductions are achieved eastbound where the impact of removing two lanes of traffic will have the least impact on congestion; westbound, where the impact on congestion is the greatest due to the changes, there are small improvements or actually a negative effect.
  • The CO2 reductions achieved from light rail can very easily be matched by a small increase in fuel efficiency.

These results indicate that transit options that increase congestion will actually see a limited or negative effect on CO2 emissions, says Myers.

Finally, while the data show a slight reduction in day-to-day emissions of CO2, it is probably not reasonable to make light rail the centerpiece of any strategy to reduce greenhouse gases, says Myers.

Source: Todd Myers, "Light Rail on I-90 Will Do Little to Reduce CO2," Washington Policy Center, September 2007.


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