Building a massive highway or bridge or subway in the United States takes a lot longer today than it did back in, say, the 1950s. Why is that?

One popular scapegoat is environmental regulation. In 1969, Congress passed the National Environmental Policy Act (NEPA), which requires all federal agencies to review the potential impacts of their actions. A very large transportation project that gets money from Congress often has to file an "Environmental Impact Statement" and gather input from the public, which can take years. And, as this chart from Nate Berg over at Atlantic Cities shows, completing those reviews seems to be taking longer and longer as time goes by:

The data comes from this America 2050 report (pdf). Back in the 1970s, finishing up an Environmental Impact Statement took just two years, on average. Today, it takes more than eight. (Keep in mind, however, that this only applies to the largest, costliest transportation projects: Just 15 percent of federal highway spending even requires an impact statement in the first place.)

Now, does this mean Congress should blow up NEPA? No. Or at least that's not what the Regional Plan Association, which published the report, recommends. The authors note that environmental rules themselves aren't chiefly responsible for the holdup. Rather, according to a survey of people who actually plan and build these roads and bridges, most of the delays come from agency problems: "administrative process bottlenecks, project management failings, or a lack of capacity among the agencies involved in the process."

In fact, the report notes, it's quite possible to build large roads and bridges very quickly under existing environmental rules. Consider Minneapolis. Back in 2007, the city's Mississippi River Bridge on I-34W collapsed, killing 13 people. It was a widely publicized disaster. Lots of headlines. What's more, Minneapolis needed to rebuild the bridge immediately — it was a crucial route with heavy traffic. So all the local and federal agencies huddled together to make it work. And they managed to leap through all the environmental hoops and rebuild the bridge in less than 14 months:

Despite its urgency, the project was not granted a single waiver or exemption from the permitting or environmental review process. It completed the same NEPA steps as would any typical transportation project of a similar scope and scale. The only difference was the level of federal leadership and advanced coordination that occurred. All federal agencies and project sponsors understood their roles and responsibility and began work immediately upon hearing of the tragedy.

All told, the America 2050 report notes, it would be a mistake for Congress to hack away at existing federal regulations — doing so would "undermine environmental protections and fail to address root causes of delay." It's worth remembering, after all, that environmental reviews can be quite valuable: The Sierra Club has compiled a dossier (pdf) of road projects over the years that were successfully altered thanks to review and public input in order to stem water pollution or to limit sprawl or to avoid disrupting scenic areas.

Instead, the report recommends "reforming the internal administrative policies, procedures, and practices currently in place." That includes humdrum stuff like "integrating environmental reviews with state and metropolitan planning requirements into a more cohesive project development process." The report offers plenty of detail on what that all means. Sadly, those dry bureaucratic steps don't make for a sexy campaign slogan. But they might help get all of our bogged-down highways and bridges built more quickly.