The biggest problems with American rail infrastructure are related to passenger service. The US has one of the largest freight rail systems in the world by whatever metric you want to use: total miles (#1), annual tonnage (#2), ton mileage (#3) or modal share (#7).

In any case, semis occupy a largely separate mode of transportation that aren't cost competitive with freight rail where it's viable. Autonomous semis are competing mainly with the limitations of human drivers, not freight rail.

Create a hub and spoke system with automated container sorting at the hubs. Basically build a national rail distribution system that works like a modern distribution warehouse. Long haul trucking should not exist.

The US already has the largest freight rail system in the world, there are just things rail can’t do

We run the largest freight rail in the world and ship more stuff via train than any other nation. BNSF Railway's revenue is $24 billion a year. Same with Union Pacific. They dwarf the major truck freight companies like Fedex Freight or Knight-Swift.

This is a good thing IMO, it’s too late to play catch up with rail infrastructure, we should just skip to the next big thing and let the rest of the world have their antiquated rail structures.