Over the weekend I was clearing out my RSS, and was pleasantly surprised to find Sunlight’s work in an unexpected place. TheWashCycle is my favorite DC bike blog, and its author has started a series of posts designed to address arguments that are commonly faced by cycling advocates. One of those is that cyclists don’t pay for roads — that the gas tax pays for them — and consequently folks on bikes aren’t entitled to the use of roads, or are less entitled to space on the road than motorists, or shouldn’t have a say in how roads are built.

As it turns out, the assumption that cyclists don’t pay for roads is wrong. The WashCycle post linked to some work that we did for Pew’s Subsidyscope project, which shows that gas taxes are paying for a decreasing share of our roads. In 2007 taxes and fees related to auto use covered only half the bill. The shortfall is made up by general revenues and debt — and though the specifics of the story play out differently from state to state it’s safe to say that cyclists pay taxes that help build roads.

I mention all this not simply to highlight some pro-cyclist propaganda — though of course, as a daily bike commuter, I’m glad to do that, too — but rather to point this out as an example of what open government data can accomplish. Kevin, who deserves credit for the analysis, assembled the above graph using statistics assembled by the Federal Highway Administration (reports HF-10, HF-210, HDF, SF-21 and LGF-21, for those of you keeping score).

I think there are two lessons that can be drawn from this, and while neither may surprise you, they’re both worth repeating. First: government data can be extremely valuable. The question of who pays for roads is one that gets brought up a lot — sometimes about bikes, but more often in a cars versus trains frame — and all that most of us have to work with in answering it are superficial intuitions and half-remembered canards. The truth is, the answer is much more complicated than most of us realize. Thankfully the Highway Administration does a great job keeping tabs on how we fund and use our roads and has been for quite some time (some statistics go back to the 1920s). And while the data they collect might not tell us exactly how to build our transportation system, it can at least let us address the question more intelligently.

The second lesson will be familiar to readers of this blog: even free data comes with a price. In order to put together this analysis, Kevin had to deal with broken HTML pages, Excel documents, and even track down a converter for some legacy Lotus 123 files. He’s a talented guy, and so all it cost him was time and effort. But still, that’s a pretty high technical bar for an important analysis — an analysis that has implications for not just bikes, but for all sorts of questions related to transportation policy, urban planning and even energy policy. Yet, as you can see from the WashCycle link, the question only seems to be examined every few years, when enough funding or talent become available to get the job done.

If we could lower the barriers to that analysis — reduce the technical cost — we’d be able to run it more often. Or in more ways. If more people were able to work on this question, it’s likely that more people would hear about the answer, which would improve the quality of our conversations about paying for transportation infrastructure. Hopefully our transportation policy would improve, too. At the very least, more people might know I helped pay for the bike lanes I use.