And if it's not the same infrastructure, we can lower the fuel cost by reducing rolling resistance by switching to steel wheels on steel tracks, and then since

And if it's not the same infrastructure, we can lower the fuel cost by reducing rolling resistance by switching to steel wheels on steel tracks, and then since no other vehicles will be on this infrastructure, we can chain multiple of the trailers together, aaaand we've invented trains. All transportation alternatives converge into trains over time, it's like carcinization but for transport.