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Cut Your Carbon: Make the Switch to Public Transit

This article was written by Erica Barnett in September 2007. We're republishing it here as part of our month-long editorial retrospective.

Taking%20Transit.jpg The single most effective way to cut one's personal quotient of carbon dioxide pollution is switching from cars to public transit. That's the finding of the American Public Transportation Association, which this week released a new report on CO2 and personal transportation. According to APTA, "when compared to other household actions that limit carbon dioxide (CO2), taking public transportation can be more than ten times [more effective] in reducing this greenhouse gas." It's something we all know intuitively, of course--driving alone has significant climate impacts even if the car we're driving is a "green" one--but it's fascinating to see the specific impacts of our driving habits quantified.

The APTA study took on four big questions:

  • How much CO2 is public transportation currently saving in the US?
  • How much additional CO2 savings are possible if public-transit use increases?
  • What's the carbon impact of a household whose members drive to work instead of using public transit, and how can households reduce that impact? And
  • Does public transit lead to better land use (and thus environmental and social benefits)?

In 2005, the APTA researchers found, public-transit use reduced CO2 emissions in the United States by 6.9 million metric tons--the net difference between the emissions produced by transit and the emissions prevented by reducing congestion and taking cars off the road. A single individual with a 20-mile commute could reduce her personal carbon production by more 20 pounds a day simply by switching to public transit. And although it's hard to precisely measure the land-use impacts of increased transit use, various studies have estimated that the number of vehicle miles traveled goes down between 1.4 and 9 miles for every passenger-mile traveled on transit.

That personal carbon reduction deserves a closer look. Twenty pounds a day works out to more than 4,800 pounds a year, assuming a 240-day work week. That impact is much greater than many other changes people are frequently encouraged to make, including weatherizing the home and adjusting the thermostat (about 2,800 pounds a year); replacing incandescent bulbs with compact fluorescents (about 90 pounds per bulb a year); and replacing an old refrigerator with a high-efficiency one (about 335 pounds a year).

But the decision to trade driving for public transit isn’t merely a matter of individual choice: the transit must be available. Typically, to make that happen, governments must support it politically and financially. Fortunately, better mass transit is a solution more municipalities are embracing, according to data tracked by the Federal Transit Administration, which include transit ridership, availability, and subsidies nationwide. According to the latest available numbers, the number of miles transit vehicles spent in revenue-generating service went up 31 percent between 1996 and 2005. Systems that were built in that period (mostly light rail) saw much larger gains: 85 percent for light-rail systems, and a nearly three-fold increase for vanpools. Buses continue to make up more than half of all transit systems nationwide, but light, heavy, and commuter rail systems continued to grow: from a combined total of 36.6 percent in 1996 to 39.3 percent in 2005.

Image: flickr/anaki

Taking Transit: The Most Effective Route to Cutting Carbon is part of our month long retrospective leading up to our anniversary on October 1. For the next four weeks, we'll celebrate five years of solutions-based, forward-thinking and innovative journalism by publishing the best of the Worldchanging archives.

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Thanks for the good reprint and original. I'm a big supporter of pubic transit in general, but concerned about overly general thinking in sustainability issues, and about sometimes-uncritical echoing of industry groups.

To wit... perhaps not all public transit is created equal? On the one hand, we have a quiet, electric-powered light rail line, anchoring high-quality dense development in urban core areas. It's all good.

On the other hand, we have a full-size diesel bus, typically around 25gal/100mi, loud beaks and engine, road-pounding, particulate- and carbon-polluting, driving a marginal suburban route with half a dozen riders. Six people in six Priuses totaling 15gal/100mi (based on 2.5gal/100mi each), seem to perform better than than the big bus in many dimensions - carbon pollution, toxic pollution, noise, road damage, etc. That big bus running largely-empty may not be all good, after all.

We need to invest vastly more in public transit in the U.S. In fact the current highway spending share and the current transit spending share need to be switched. But as we imagine and design this necessary new US future - and contemplate the possibility of such 10x+ investment - we need to be increasingly careful, too. Public transit needs to be intelligently, critically designed and located - much more so, if/when we succeed in getting much more of it.

Let's give public transit the same kind of honest love we give green building: probing, thoughtful evaluation; attention to independent information sources, even third-party certification; careful parsing of options and alternatives within the righteous sense of overall good.

Posted by: Kevin Matthews on 27 Sep 08



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