[DoesntMatter22]

You think a completely reasonable standard is for a train to average 58 mph all the way across the united states without stopping?

What about all the slowdowns due to extremely rough terrain? The fact people have to be swapped out? The fact that not all cars are going all the way across the country and also have to be swapped out?

58mph average is insane.

[Retric]

Train’s don’t need to slow down for rough terrain because they can’t handle rough terrain and either route around it or tunnel through it. What they do need to slow down for is the rail network itself.

Poor track conditions, missing block signal systems, and Trains without an automatic cab signal, automatic train stop or automatic train control system "may not exceed 79 mph."

Freight trains really could travel a mostly Class 6 network at 120MPH in the US, we have regulations all the way to class 9. They don’t because that’s not rail is optimized for.

[DoesntMatter22]

So as you said it's not actually reasonable to think a train is going to get across the US in 48 hours.

Trains have to slow down a lot when going through rough terrain because there are curves involved. You can't go 80mph.