I just wanted to second Iain’s post, and to mention that in the current dead-tree issue of National Review I offer a breakdown of the various environmental hurdles that transportation-infrastructure measures must clear.

Here’s a quick summary. As Iain mentions, the National Environmental Policy Act, or NEPA, requires that projects undergo various degrees of environmental review; for big projects, this entails an environmental-impact statement and a public-comment period. NEPA doesn’t mandate that builders not harm the environment–just that they take such harm into consideration–but if an environmental group can find some flaw in the NEPA process, it can sue. As a result, builders typically “bulletproof” their documents, including every conceivable problem and taking hundreds of pages to do it.

In addition, NEPA serves as an umbrella for other regulations. In the NEPA document, builders must explain how they plan to comply with laws like the Endangered Species Act, the Clean Water Act, and historical-preservation laws.

Also, projects that receive federal funding–like, say, stimulus money–must pay workers the “prevailing wage” under the Davis-Bacon Act, hire minority contractors under the Disadvantaged Business Enterprise program, and buy only American steel under the Buy America program.

On top of all this, there are local and state regulations to deal with. So, when it comes to big projects that haven’t already undergone NEPA review, there’s very little hope of spending much money very quickly.