Two things of note happened in the Y axis of the above graph.
1. Earmarks disappeared from the Congressional toolbox. The sole job of a congressman is to get good stuff for their district; its this correlation of self-interests among potential competitors that makes the American system work. I know we all looked down on earmarks as a hallmark of the unacceptable corruption of a previously high-minded institution, but the institution was never that high-minded and it was never designed to be.
2. Americans elected a black guy President, and he was promptly tagged as corrupt and likely to hand out money to poor people who were undeserving because they are poor.
So what you see in that graph is a successful takeover of infrastructure spending by people who have power not by virtue of their elections - the President, the House - but by virtue of their institutional longevity and ability to work the system from the inside, i.e. the Speaker of the House. And of course the thorazine wing of the Republican party is what enabled Newt to gain and hold the power, and for some reason - not his race and your racist for suggesting it! - they hate Obama, and like Frankenstein's monster or Godzilla they've now decided to wreck everything in their path because that's all they were really designed to do.
(I think that might be the best way to understand the thorazine wing. They're not there because they have ideas about government or the inclination to govern. They're there because they smash things, or at least up until recently threaten to. With strong leaders they feel warm and cozy because that is, after all, what they really want - a strong leader who is of the people but also above them, irreproachable in morals but not afraid to wield his disapproval like a sword, a kind of Jesus Christ via 1928 Munich. With weak leaders like Boehner they run amok wrecking things, asking stupid and irrelevant questions, and generally doing the things the strong leader threatens they will do. But its always a mystery when they do, because we're supposed to believe these people have rich inner lives and read Locke and Burke in their spare time when really they're not much more than Christian Dominionist robots.)
Its going to be an interesting 20 years, as bridges start to collapse, interstate highways crumble, and airports fall apart, all because Newt Gingrich wanted to rule the world and the Washington establishment felt uncomfortable calling out the racists in their midst. These idiots have no problem using my tax dollars to air condition tents in the desert, but making sure my kids' schoolmates aren't hungry during the day and that their schools aren't falling apart is bleeding-heart liberalism.