Socialism?
The current transportation system is largely through taxes and no not gas taxes. The way it works is that gas taxes and Federal funds are used to pay for interstates, arterials, and collector roads in almost every state and MSA in the US (pretty much any municipality big enough to apply for transportation grants.) The Federal government then helps fund road construction while states and consequently cities take the maintenance burden on. Maintenance itself is paid for through a combination of gas and state taxes along with Federal grants which are also based on other taxes.
The current system is already largely funded through taxation. It's just a matter of whether you think those taxes should be spent on creating and maintaining roads or whether you think they should be spent on transit. The closest to use taxes we have is the gas tax and the Federal one hasn't been raised since 1993 (state taxes differ per state and have been raised more recently.)
If you really want to move away from "socialism" or whatever, then make infrastructure toll based in the US. You'll find though that toll roads are highly unpopular.