Around half the cost of a modern motorway is in the pavement -- the bit you actually drive on -- and nearly all of that is to make it resist truck loading. The number of cars, including electric cars, using a motorway is not considered *at all* in its pavement design.

Interesting thought experiment: What would a motorway cost if all vehicles exceeding say 5 tonnes GVM were reliably excluded? Obvious: *Much* lighter pavement, lighter bridges, lighter traffic barriers.

But what about: Narrower traffic lanes, lower overbridge clearances, shorter acceleration lanes, steeper ruling gradients. Answer: Maybe not half the cost, but getting towards that.

Point: The hidden subsidy to the trucking industry isn't large, it's gigantic -- just in the road cost component -- yet we do not proposed new taxes on trucks.