Trump’s proposal provides for public private partnerships, P3s. I would imagine there a lot of firms that would be happy to front the money for some construction in return for the opportunity to collect tolls on those frequently clogged highways.
We already have toll roads in SoCal. Most new highway construction here has been toll roads or toll lanes.
This article is calling for the ability to use tolls to rebuild and maintain our older Interstate freeways.
I can see an unholy alliance of libertarians and radical greens pushing for this. The libertarians would love the Interstate financing to be tolls rather than taxes, and the greens will seize any opportunity to control your driving and price you out of your car if possible.