A month before taking office in 2009, Barack Obama promised “a bold agenda” to create jobs rebuilding U.S. roads and bridges with “shovel-ready projects.” Almost two years later, Obama conceded what Donald Trump may yet learn: “There’s no such thing as shovel-ready projects.”

In a Feb. 28 speech to Congress, Trump said he wants legislation to support $1 trillion worth of investments rebuilding roads, bridges, tunnels, airports, and other crumbling infrastructure, putting millions of Americans to work in the process. But as Obama found out with the $787 billion federal stimulus bill, lining up environmental reviews, permits, and the other approvals required for a large-scale project can consume years—in some instances even decades. William Ibbs, a professor of construction management at the University of California at Berkeley and president of Ibbs Consulting Group, points out that it took 23 years to replace the San Francisco-Oakland Bay Bridge after it was damaged in the 1989 earthquake.

Big, transformative, economy-boosting projects don’t happen just because they’ve received funding, says Sarah Kline, a fellow with the Bipartisan Policy Center, a Washington-based research group focused on infrastructure. “Those types of projects are not sort of hanging around just waiting for money to fall from the sky,” she says. “There needs to be a longer-term outlook this time around.”

Trump hasn’t detailed how his infrastructure plan will be funded or what types of projects it will include. Republican and Democratic leaders in Congress disagree about how much new federal spending should be included; Senate Majority Leader Mitch McConnell has said he wants to avoid “a trillion-dollar stimulus.”

The American Recovery and Reinvestment Act of 2009 budgeted $69 billion for infrastructure improvements, including $48.1 billion for transportation. A 2011 Government Accountability Office report found that while the recovery act helped fund tens of thousands of jobs, its “long-term benefits are unclear.” “I believe we missed an opportunity to do more,” Representative Steny Hoyer, the Maryland Democrat who was House majority leader at the time, said at a Feb. 7 event at the Brookings Institution in Washington on funding infrastructure Read more..