I wonder why.
Another issue is the size of trucks. The state where I lived:
* Truck size was limited, large trucks were only allowed on one Highway. Goods were transferred to smaller Trucks for transport to factories.
* Driving trucks on Sundays was not allowed.
* Large Trucks were not allowed on City Streets. Since this happened it is open season on bicycle riders.
Reagan de-regulated and Trucks can be any size, plus they can clog the roads on Sunday. The last item I do not know when it was enabled, but it happened after Reagan.
I now heard of trucks with 3 trailers but never saw one. I think it is about time we limit sizes to what existed on the 60s. If you need 3 trailers, time to go back to freight trains.