To hear some Republicans tell it, pesky environmental rules are a major reason why it takes so long to build highways and bridges. That’s why the GOP’s transportation bill would speed up reviews for various projects. But is this theory true? The evidence, it turns out, is hard to come by.

Don’t blame me for those orange cones. (Matt Cardy/Getty)

In 2000, the Federal Highway Administration conducted a survey of 89 large projects that had suffered long delays, and found that just 19 percent were bogged down due to environmental concerns (resource agency review, endangered species, or wetlands). The vast majority of the projects were delayed because of lack of funding or because they were a low priority for the state (32.5 percent), because of a local controversy (16 percent) or because the project was simply very complex or had shifted in scope (21 percent). Another 2005 study focused on Oregon found that environmental concerns were not a major source of delay — and that “efforts to streamline the process may not alter overall timelines.”

Now, these studies only examined a sampling of projects. And there are no doubt ways to speed up the environmental review process. When the Government Accountability Office examined this question in 2003, they found agencies and industry groups complaining about all sorts of procedural headaches, from a shortage of staffers to poor agency coordination to the time it took to obtain wetlands permits. (Though, the GAO found, almost no one could say “how much time these aspects added.”) Still, it’s remarkable how little data there actually is on this question.

That hasn’t stopped the House from crafting a transportation bill that would try to significantly streamline the environmental review process. “The average federal highway project takes 15 years from concept to completion in the U.S. because of excessive regulations,” said John Duncan Jr. (R-Tenn.), chair of the House highway and transit subcommittee. Among other things, the House transportation bill would set a 30-day deadline for approval after the environmental impact statement is ready. States would also get more leeway in determining what projects don’t need environmental oversight. Bloomberg has a fuller breakdown here.

Deron Lovaas, transportation policy director for the Natural Resources Defense Council, warns that the bill could lead to projects that move ahead before proper vetting. “You open the door to faster paving,” he told me, “but that could lead to serious problems if you then have a neighborhood or community that’s not happy with the project.” What’s more, there’s the risk that states with lax environmental laws could push forward projects that end up being quite damaging to local wildlife or wetlands or water quality or so forth. (The Sierra Club has compiled a dossier of road projects over the years that were successfully altered thanks to environmental review and public input to include wildlife corridors or to limit sprawl or to avoid disrupting scenic areas.)

The Obama administration, for its part, has taken a different approach to this issue, selecting 14 specific infrastructure projects that have been especially plagued by delays and pushing those through expedited approval. Many environmental groups and transit advocates prefer this strategy of focusing on the tiny subset of projects that are actually causing problems rather than broad legislative changes.

But the bottom line is that this issue needs a lot more study than it’s actually received. The debates over transportation bills since 1988 have all focused on streamlining environmental oversight, yet there’s never been a full analysis of whether tweaks to rules have actually speeded up delays. The GAO is reportedly now conducting an in-depth study on this issue at the request of House Republicans. But that report won’t be out until spring at the earliest, after the transportation bill’s been put together.