It is a serious problem. I did some poking around and came up with a cost of over $3 million per mile to build an interstate road. That's a lot of money. Our roads both primary and secondary, state and Federal are deteriorating quickly. Just drive along and look at the bridges you go under, rust and concrete breaking up. I was on I70 a couple of weeks ago and was forced to drive the MH in the left lane to avoid all the potholes.
I believe there is enough money to maintain our roads. The problem is that there is too many pork barrel projects, fraud, etc. Our government on all levels skims too much off the top before sending what is left back to us. Government needs to focus on providing basic services to the people and quit playing all the political games.
We probably will have to restructure our road tax system in the future. My guess is that vehicles in the future will download information about miles driven, and we will pay taxes on that plus weight.