Pretty much all they're planning on doing is maintaining what exists and adding in some stupid trains.
If that's the case then the responsibility for maintaining roads and bridges should fall back to the states.
If a state chooses not to maintain its roads then truck traffic will avoid it, tourists will avoid it, etc.
The market should be able to keep states honest and maintain reasonable roads if they want to keep their own people happy and business thriving.
Maintenance is one thing, but this country's highway needs go way beyond that. A highway generally has a functional life of about 50 years, which means the interstate highway system -- now 59 years old -- is now in a state where it is effectively being reconstructed in its entirety. That is an enormous, expensive undertaking that will eventually cost more than the original construction of the system.