Assuming an unlimited supply of semis and drivers to fit the demand. With limited supply big companies will be able to a compete for the available trucks at really high prices but small-mid businesses will be left out.
Small-mid businesses generally are not shipping on rail to begin with, unless they've been bundled as part of a larger shipment by an intermodal carrier. If you've ever tried to talk to a rail carrier, they really don't want to deal with companies under a certain size.
>Assuming an unlimited supply of semis and drivers to fit the demand.
If the US really wanted to get it done, they could involve the army and various state national guards. They have tons of trained semi and heavy truck drivers, way more than most people would assume. Most states also have tons of trained drivers for their massive snow plows and highway repair trucks and stuff. The only thing stopping these massive projects is money and lack of imagination.