Why is it that stupid ideas get all the air time?

For months, fellow climate geeks have been telling me that road-builders — and the politicians who love them — have started to make a startling claim: namely, that widening a congested highway will help curb global warming. By reducing stop-and-go traffic, the argument goes, cars will operate more efficiently and waste less fuel. So if you want to save the climate, you’d better widen that road!

To me, this sounded too dopey to be worth refuting. I mean, sure, over the short term, congestion relief might help a bit. But what about all of the emissions from road building itself — and, more importantly, from the extra traffic that will inevitably fill those new lanes?

But despite its obvious absurdity (or perhaps because of it) this particular suburban legend seems to be getting a life of its own. Just take a look at what British Columbia’s Premier had to say recently about a proposed highway widening project in greater Vancouver, BC:

Campbell … continued to defend the [highway] project … saying that it will reduce emissions and make room for rapid-bus services along the highway.

Because I couldn’t find anything addressing this issue online (academics have better things to do with their time, apparently), I spent a bit of time running some numbers. You can read the full report here (PDF) if you’re a real geek. But in a nutshell: congestion relief may offer some slim GHG benefits over the short term; but these benefits are absolutely dwarfed by the emissions from road construction and, more importantly, by all the extra traffic that fills the expanded roadway.

In fact, it looks to me as if adding a single lane-mile to a congested urban highway will boost CO2 emissions by at least 100,000 tons over 50 years. And that’s making some pretty optimistic assumptions about fuel economy improvements.

So now, if anyone out there in Grist-world hears this particular suburban legend, you’ll have some numbers you can use to smack it down.