Yes it is. Your long slow moving train is now blocking other long trains from passing (since rails are rarely two way). Nevermind that the train would have to s

Yes it is. Your long slow moving train is now blocking other long trains from passing (since rails are rarely two way). Nevermind that the train would have to stop entirely and lose all the energy efficiency in the process). Constructing new rails is expensive and difficult since rails have to be nearly level with very low grade. You are handwaving about something you know nothing about and I suggest you read more into civil engineering, civil construction, and rail construction. Union Pacific will spend billions just to get roads reconstructed to move under or over train tracks so they can save a couple minutes on a delivery route. It's extremely difficult to build roads around or near freight rails because of these constraints and vice versa. Have you even compared a map of the freight rail lines in existence and their current stopping points versus the interstate and US highway system?