If that were the case the story would just be "18 lorries are going to do a boring trip", and there wouldn't need to be any special plans made for road use at all.
> "around 20 super loads are being ferried across Ohio's roads by the Ohio Department of Transportation after arriving at a port of the Ohio River via barge. Four of these loads, including the one hitting the road now, weigh around 900,000 pounds — that's 400 metric tons, or 76 elephants"
So not all eighteen are quite so huge, but the biggest four are roughly 10x heavier than a typical large lorry(/truck) can handle.