Road use taxes?

Bridge collapses out west.  We have pot holes big enough to swallow cars.  Exactly what does the government do with the gas taxes, the taxes on the trucks, the registration fees and all those other fees and permits they charge for trucks and other vehicles to use the roads?  I'm guessing it's not maintenance like it was suppose to be.  Probably into the black hole of social programs to buy their votes in the next election.