Well, one of the differences between the US and UK is the US is much larger, and the long-haul 18-wheeler routes are going to take longer than a weekend to drive and back. Going between, say, Chicago and NYC takes ~12 hours... not counting stops. And that's one way!
It only takes one choke point or low bridge or prohibited route to ruin your whole trip. While 99% of US roads may be bigger and wider, 1% of a 400 mile daily trip can cause major problems.
Aren’t American trucks bigger though? Seems like the economics would encourage companies to make the biggest truck that can physically fit on the roads, to maximize cargo per driver hour.
Slightly bigger, because in the US the regulation is on trailer length, whereas European regs are on total length. So Euro trucks are all cab-over designs, while American trucks are generally engine-in-front (easier to access for maintenance). But unless you're talking about a double trailer, not much difference.
The problem is a lot of American roads have poor clearance. You can find a lot of images online of trucks that have been opened like a sardine can along the top due to hitting a low bridge. You can't make the truck too long either or else it will be unable to turn on right angle intersections. When they deliver big things like wind turbines on American roads, its can be an extremely slow process with engineers spotting each and every single turn along the route.
That's an interesting point. It would seem that the idea truck would have the highest possible cargo to truck weight ratio for profitability purposes. The square cube law would seem to indicate that larger trucks are heavier, but add much more cargo space to compensate.
However, larger engines could be less efficient per pound than their smaller counterparts. My intuition is that the opposite is true, but I could definitely be wrong on that.
true, but then in the UK you're working with roads that aren't even really designed to host trucks in the first place. American roads are pretty grid-ish, British roads are all over the shop and much more organic in structure.