By Colby Itkowitz, CQ Staff

The economic stimulus package that Democratic congressional leaders are talking about pushing after the election will most likely include a big investment in infrastructure projects. But some experts, including the chief economist for the Transportation Department, think such highway and mass-transit projects are too slow getting started to be the kind of energizer the economy needs right now.

The $150 billion plan unveiled last week by House Speaker Nancy Pelosi of California — which has been endorsed in its broad outlines by both Senate Majority Leader Harry Reid of Nevada and the party’s presidential nominee, Sen. Barack Obama of Illinois — is expected to pour federal funds into “ready to go” infrastructure projects that could be up and running within 90 days.

DIG IN: A stimulus bill might help transit projects, like this in Brooklyn. (BLOOMBERG NEWS \ STEPHEN HILGER)

The American Association of State Highway and Transportation Officials has compiled a list of more than 3,000 projects that states say are just waiting for funding so they can begin work. Proponents of the plan say thousands of new jobs would be created as a result, an issue that the House Transportation and Infrastructure Committee will review in a hearing on the stimulus plan scheduled for next week.

The research and policy director at the liberal-leaning Economic Policy Institute, John Irons, says that if the nation goes into a recession — and there’s a growing consensus that it’s already there — employment opportunities will be needed not just in the short term, but for months down the road. “With recessions the job market takes a lot longer to recover,” Irons said. “So whatever we can put into the pipeline, it’s not like we won’t need it in six months or a year.”

But Transportation Department economist Jack Wells says that even highway projects on a fast track will take too long to get going to provide a meaningfully quick spur to the economy. “It takes a long time for these jobs to be created,” he said. “Infrastructure construction requires a long series of steps to plan, design, get environmental clearance on and construct.”

According to Wells, such delays mean that only 27 percent of the funds being proposed in the Pelosi package would end up being disbursed within a year of the law’s enactment.

Wells, of course, works for a Republican administration, and Republicans generally prefer tax cuts to public works as a way to kick-start an economy nearly paralyzed by the credit crisis and stock market slump. Indeed, although the House passed a stimulus bill in September with $18.5 billion for infrastructure projects, the Republicans have now drafted their own competing version that would not include any funds for public works.

Robert Poole, the director of transportation studies at the Reason Foundation, a free-market think tank, says infrastructure spending as a means of stimulus tends to get into the economy when the recession is already over. “Recessions typically last two to three quarters at most,” Poole said, “so if it takes a year, then it’s not doing what it’s intended to do.”

Indeed, research shows that Congress in most cases has passed stimulus legislation near the end of recessions, sometimes even after the economy has turned around.

“There are legitimate questions about how fast even the fastest projects can stimulate the economy,” says Chad Stone, the chief economist at the Center on Budget and Policy Priorities, a socially liberal but fiscally conservative think tank.

Though some economists say infrastructure spending is a greater stimulant because the government is putting money directly into the hands of business, Stone says that “the infrastructure spending is going to have less bang for the buck than, say, temporary increases in food stamps.”

But the relative speed of highway work and other infrastructure projects might also have to do with motivation. Irons points out that Minnesota replaced the Interstate 35W bridge over the Mississippi River in Minneapolis within a little over a year of the bridge’s collapse in 2007.