High gasoline prices in the United States have prompted a sustained cutback in driving, and the resulting dip in revenue from the federal gas tax is already canceling plans for infrastructure projects due to lack of funding. Right now, roughly one-quarter of bridges in the U.S. are either “functionally obsolete” or “structurally deficient,” and one out of every seven miles of U.S. roads is rated “not acceptable,” according to government assessments. Some $225 billion a year is needed to keep U.S. transportation infrastructure in tip-top shape, and current spending is less than half that. Now with the dip in federal highway funds, as well as rising construction costs, the outlook for many aging U.S. roads and bridges is uncertain at best unless Congress can pass funding soon. The National Highway Trust Fund is expected to accrue a deficit of at least $5 billion next year. To ease the funding crunch, the Bush administration wants to ease restrictions on charging tolls for interstate highways and make it easier for states to use private funding for infrastructure improvements.