Incidentally, in the Post piece on pork by Michael Grunwald, linked immediately below, he offers a culprit for some of the big ticket items in the transportation bill:

There is little evidence that Republican leaders pushed TEA-LU because they love sprawl. They simply saw the bill as a politically popular goodie bag for their members, as well as special interests that benefit from new roads — home builders; oil companies; and a coalition of cement producers, engineering firms and other highway-related groups that led the push for the bill as Americans for Transportation Mobility.

I’ve added the link; a quick visit to the site shows that those wishing to join should contact the U.S. Chamber of Commerce’s Transportation and Infrastructure segment of its Congressional & Public Affairs (translation: lobbying arm) and a list of the members which the Chamber publishes. “Americans for Transportation” don’t show up as an independent political action committee at the federal level, nor as a 501(c)3 nonprofit, nor as a 527 political organization. It doesn’t appear to lobby Congress (although if it’s part of the Chamber, which spends a fortune of its own on lobbying, the lack of a registration doesn’t mean that their issues were not pursued on Capitol Hill.