Work is expected to start late this year to add toll lanes on Interstate 77 through Charlotte.
The North Carolina Department of Transportation says the project will widen 26 miles of one of the most congested highways in the state.
The project involves converting the existing high-occupancy-vehicle lanes to tolls and adding more toll lanes.
Vehicles with three or more people will still be able to use the toll lanes free.
The state will contribute $88 million for the work. That's less than the $170 million that had originally been projected.
Construction is expected to begin in December.