Transurban wouldn't do it by themselves...they didn't even fund the existing Beltway HO/T lanes fully by themselves...several hundred million dollars for the HO/T lane project came from VDOT.
Agreed that a consortium of private companies would likely have to undertake rebuilding the American Legion Bridge. If only the private companies pay for it, then likely the whole thing would be tolled. If VDOT and MDOT end up contributing to the project, then the main lanes should continue to be free while the private companies can toll the express lanes/widened part.
They would need to conduct a full NEPA EIS/location study process first to the point of having an FHWA approved Final EIS and Record of Decision. That took about 8 years for the I-495 HOT Lanes project between I-95 and VA-193, which is about what it takes.
I seriously doubt that the Maryland General Assembly would give its consent to a Public-Private Transportation Act (PPTA) type of deal to have a private-sector firm be awarded a long-term concession for any highway project in the state (the Maryland Department of Transportation had awarded a PPTA-type concession agreement to a consortium for the Purple Line light rail project, but that may not happen at all at this point, given legal challenges in the U.S. District Court for the District of Columbia).
There is
no analog to Virginia's PPTA in Maryland, so I believe that's a non-starter. Now
Virginia might make a deal with Transurban to extend its toll lanes concession up to the Virginia side of the American Legion Bridge, but I believe that is as far as Transurban will get. Anything from the first expansion joint on the Virginia side north is up to Maryland.
Agree that a NEPA process will take (at a
minimum) three to four years, and likely several more than that.