All the gas tax talk has stirred up a storm. Whatever you think about the candidates' proposals, however, their debate has illuminated an urgent reality: If the U.S. government continues with its current transportation policies, it will undermine the social and economic security of our workforce and accelerate global climate change. We must chart a new course, rebuilding America's overburdened and, in many cases, obsolete transportation infrastructure while addressing these two 21st-century imperatives.