1. Millions of people looking for work
2. Hundreds of billions and/or trillions of dollars desperate for some way to be spent (as evidenced by the historically low rate of return on bonds)
3. Cities with inadequate flood protections, bridges we all drive on which aren't up to code, and slower internet than much of the developed world.
Romney says he's for infrastructure spending, but given the massive challenges he'll face to pay for his tax rate cuts, increased military spending, and pay down the deficit, it's seems likely that plans to increase domestic discretionary spending will be first on the chopping block.
This is one of the many reasons why Romney's vagueness is so frustrating. It allows him to say "sure, I'm for infrastructure spending!" without showing where he'd get the money from. It deprives voters of a chance at real discussion. Everybody's for giving citizens benefits if there doesn't have to be discussion of costs. It's figuring out the balance between competing possibilities that requires debate and leadership. Romney provides neither.