Rolling resistance is usually a bigger issue than aerodynamics for semis. Rolling resistance is at their lowest when tires break in...dropping by significant margins as far as I remember. I wonder if LRR tires are being developed (exist?) for the industry...
I do agree that rail is more efficient than trucking, but isn't (large-scale) shipping even more efficient than rail? How about the marriage of the speed of air shipping, capacity of the trucking industry, low congestion of shipping, and some of the efficiency of rail...the ekranoplan.
Ekranoplan
Just a little off topic...
- LostCause