Falling revenues and budget cuts are causing states from Texas to Maryland to rethink funding sources for road and transportation construction. For instance, South Carolina needs to generate about $30 billion in revenues over the next two decades to fund bridges, roads and mass transit. By 2015, Texas' $10 billion annual transportation budget will cover only road maintenance -- not expansion or construction of needed new roads. Virginia is looking to raise $500 million a year in new revenue to devote to reducing traffic congestion.