Fewer cars are on the road, but greenhouse gas emissions are not the only thing evaporating. A key construction account of the federal Highway Trust Fund is also drying up. The fund âÄî which is financed through federal gas taxes âÄî aids road and bridge construction projects across the country. But higher gas prices have spurred relatively frugal driving habits lately, draining the federal Highway Trust Fund to insolvency. The shortfall threatens to leave meager state budgets scrambling to finance already-harried construction late in the season. The lack of funding for current construction projects worries politicians, business leaders and observers who see healthy transportation infrastructure as the backbone of the U.S. economy. To ensure completion of local infrastructure projects, some have suggested reallocating funds from the Federal Transportation AdministrationâÄôs surplus mass transit account âÄî thus taking money from transit projects across the county that serve an attainable solution to the countryâÄôs infrastructure and energy woes. The House of Representatives nevertheless passed legislation (H.R. 6532) to transfer $8 billion from the federal General Fund âÄî a separate coffer funded by income taxes âÄî to the ailing Highway Trust Fund. The Senate has yet to pass the measure but President George W. Bush said he would veto it. Robbing federal mass transit aid, which may fund half of the $915 million central corridor light-rail line, is no solution. The trend behind the Highway Trust Fund shortfall âÄî fewer cars on the road âÄî underscores the necessity of mass transit expansion, not reduction. As gasoline prices rise, so does the demand for public transportation. Investment in such infrastructure pays hefty dividends: It keeps more cars garaged and slows greenhouse gas emissions, not to mention wear-and-tear on relatively high-maintenance roadways. Certainly, the gas-tax revenue structure of the federal Highway Trust Fund should be revamped as gas prices rise and fuel-efficient autos incline toward ubiquity. But for now impel your well-rested senators to pass H.R. 6532 and keep mass transit funding up to speed.