This does not address a larger question: how much does a mile of road cost to keep ? This is the installed base question. Consider the amount of road that has been built out in the US relative to the populations that road is serving. Maintenance and expansion is paid out mainly from state and local taxes. That's an enormous civilizational overhead the US contends with, not to mention the economic cost of a large port…
More importantly if we focused more on making transport costs in-line with the damage they do to the road surfaces (not to mention the environmental impact of long and short haul trucking, plus the traffic) instead of city/suburbia none issue, perhaps we'd all be a bit better off.