Widening highways does not save fuel

Over the weekend I posted a mini rant here on the subject of highway widening. To make a short story even shorter, I was pissed that instead of funding rail projects, or repairing existing highway infrastructure, some of the stimulus money being spent here in Michigan was going toward the widening of highways. In the comments that followed, our friend Murph, I thought, had a great response to someone who had suggested that perhaps widening highways would lead to fewer traffic jams, thereby saving fuel. And, as I didn’t want to leave it buried in the comments section, I thought that I’d move it up here to the front page… So, here it is.

A fair assertion, but not backed by data. For the full story on traffic backups, I’d recommend Anthony Downs’ Still Stuck in Traffic, which is a pretty comprehensive and empirically-backed examination of various “solutions” to traffic congestion. (Relevant bit: widening roads works for a few years, but the excess capacity induces demand that quickly leads to the road being just as congested as it used to be.)

I don’t know much about the specific project – but “widening an interchange” is a little more complex/expensive than just adding through travel lanes. But, for reference, the cost of widening a freeway is in the range of $2.4m-$6.9m per lane mile. For reference, it looks like the annual capital budget of Kalamazoo Metro Transit is about $9m, so this interchange project could cover about 5 years worth of transit capital improvements for the Kalamazoo area – transit improvements, incidentally, being among the few things Downs shows to be effective in actually reducing road congestion.

Finally, look to Seattle’s experience in late 2007, where the public resoundingly voted down a transportation bond for the reason of “too much road spending, not enough transit spending”. (Generalizing, sure, but that’s what every single newspaper’s editorial board was saying.) While the measure was under consideration, a number of sources debunked the idea of highway congestion relief reducing greenhouse emissions. See, for example, the Sightline Institute’s piece, resulting in a prediction that each lane mile of highway expansion yielded, over 50 years, a net increase of 116,000-186,000 tons of CO2 emissions, even assuming that emissions per mile drop to 1/3 of current over that time. Or, in other words, “not as much as a coal-fired power plant, but worth being concerned about. “

So, to sum up, yep, you’ve nailed the typical traffic engineer’s thinking – as long as we’ve got the contractors out there anyways, might as well have them widen the road, right? More road = less congestion, assuming everything else remains constant. Unfortunately, nothing else is constant, so the traffic engineer’s short-term gains end up consumed in the long-run, much to the consternation of transportation planners who watch this cycle happen over and over again…

So, there.

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  1. Radioscrotum
    Posted June 16, 2009 at 1:01 am | Permalink

    So should we make the highways narrower?

  2. amused1
    Posted June 16, 2009 at 6:48 am | Permalink

    Well, in my defense, I’m not an engineer and my intentions were good. Which made me think of the old saying about good intentions and hell. Which, in turn, made me wonder, if the road to hell is paved with good intentions is the path to heaven a rail line? This thought, of course, led me to consider the classic novelty song “Pardon me boys, is that the Celestial Choo-Choo?” Which, you’ve no doubt noticed, neither rhymes nor scans.

  3. Van
    Posted June 16, 2009 at 11:08 am | Permalink

    What if we pave new lanes, but we do so with the bodies of SUV drivers? Has anyone done that math?

  4. T-Mock
    Posted June 16, 2009 at 4:05 pm | Permalink

    I for one would support legislation to fill potholes with the bones and heads of Hummer drivers.

  5. Michelle
    Posted June 16, 2009 at 9:32 pm | Permalink

    I can’t be having a child. How can I be having a child?

  6. Posted June 16, 2009 at 10:10 pm | Permalink

    This is another one of those instances where I love a piece of spam so much that I can’t make myself delete it. I just love the idea that a young mother, struggling with an unplanned pregnancy has come to my site to leave a comment in a thread about highway widening… And I’m sure there’s a joke in there somewhere, but I don’t think it’s necessary.

  7. amused1
    Posted June 17, 2009 at 7:56 am | Permalink

    Somehow I would have thought a cialis ad more appropriate for enlargement issues.

  8. Constance
    Posted June 17, 2009 at 9:34 am | Permalink

    How? Hmmm. My guess is that someone – probably a male human – ejaculated inside you, my dear. I hope that helps.

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