Wednesday, September 9, 2009

Infrastructure Needs to be Factored in on Long-Term Transportation Cost/Carbon Emissions Calculations

Tracy White recently left a comment on an old blog post of mine that discussed the per-mile Carbon Dioxide emissions of different modes of travel. She brought up an excellent point that infrastructure costs and resource-use needs to be taken into account in cost-benefit analysis.

She even conveniently linked to an abstract of a research paper that indicated that adding such information to the analysis can significantly add to the lifetime energy use and greenhouse gas emissions (GHG). The study's abstract finds... "that total life-cycle energy inputs and greenhouse gas emissions contribute an additional 63% for onroad, 155% for rail, and 31% for air systems over vehicle tailpipe operation."

This seems like a a substantial impact... and I'm sure that it is. But the headline numbers touted in the abstract can be misleading. Now, I will admit that I have not taken a look at the full text of the study. Rail's impact on a per mile basis is much lower than that of cars, especially SOVs. It is because rail starts out at such a smaller GHG impact that the increase is so much higher when infrastructure is taken into account.

I'm sure that rail's lifetime environmental impacts are still much lower than that of vehicles, and from the research I have seen that is what people are finding. I'll have to dig into the study a little more when I have the time. Thanks Tracy for bringing up a great point that needs to be considered in these types of issues.

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