While I agree with the first half of your post that I91 was designed for 120K(at least)and local roads are all over the place design wise.<quoted text>
Another thing to remember is that the diesel fuel taxes have been dropping huge revenues into the Vermont coffers for decades with a small percentage only being used to repair the roads. In other words the revenues to repair any damage by trucks has been available for a long time but spent on other things.
The rail situation is a disaster in the country. Unlike the highways every tom dick and harry small RR owns it's chunk of rail which is of widely diverse quality. Using rail may be slightly cheaper in some cases but the logistics can be nightmarish. Hence trucks. The first step would be to nationalize ownership of the rails...now who wants to tackle that?
I don't think you( and most other people) really realize how much these interstates cost to construct and maintain. The taxes on fuel don't even come close to paying the freight, maybe the interest on the debt and the ongoing costs like snowplowing but that about all. Anybody here care to wager how many hundreds of millions of dollars rebuilding the "williams street bridges" are going to cost ?
The socialist highway system (modeled after the socialist nazi german autobahn) is one of the many ways the federal gov't is bankrupting the nation. The gov't works very hard to keep the real costs of the interstate highway hidden from us, by deferring maintenance to the next generations a problem delayed is a problem politically solved. The railroads tried the deferred maintenance idea in the 50's and 60's and it still landed them in bankruptcy in the 1970's
We need to go back to the privately owned tax paying railroads nationalizing them is a step in the wrong direction. The logistics of railroads were not nightmarish 60 years ago. The privately owned railroads were unable to compete under heavy heavy federal regulation by the ICC who set limits of what they could charge for freight, unions who made them inefficient, and competition from non tax paying publicly funded socialist highways. Trucks became popular due to cheap fuel and subsidized right of ways resulting in artificially cheap transportation cost.
If traffic were to return to the privately funded tax paying railroads those who have been unable to invest in their ROW's would have no problem reinvesting in their physical plant. Many many railroads( mostly out side of NE) have kept their tracks and great working order. The private ownership system of railroads worked great for over 100 years in this country until socialism (subsidized highways and airports) ran them in to the ground