If approved, the five construction packages would total $19.9 billion.
About $4.4 billion of that is already authorized.
Under the proposal, the main terminal would be expanded, Concourses A and B would be renovated, the automated train would be extended, and the remaining concourses would be completed. The people mover is the automated train that carries passengers between the terminals and the concourses.
Trump said in late July the project would add over 5 million square feet of built or refreshed space. The project would also tear down Concourses C and D, while keeping what the authority called the "iconic original terminal that first made the airport an architectural landmark."
The plan calls for demolition of Concourses C and D beginning in 2031.
The replacement is a regional concourse with 33 gates. The projected price tag for that phase is about $2.3 billion, and construction on the new concourse is slated to start in 2039.
In the US, airport projects are typically funded through municipal bonds, and Dulles is returning to that market. Grants and passenger facility charges would cover the rest. Passenger facility charges are the fees added to airline tickets that help pay for airport improvements. The authority's most recent bond sale was last summer, to help fund airport work around the region.
The bigger picture: There is already a $7 billion capital plan under way at Dulles. The $7 billion plan includes adding a concourse, building another runway, extending the passenger train, and creating more parking.
The new proposal stacks on top of that. The Transportation Department puts the full Dulles effort above $20 billion.
That count includes extras like a new lounge and a parking garage. Those items are not part of the authority's $19.9 billion proposal.
According to the Transportation Department, the authority will coordinate with airlines at Dulles to pay for the planned concourses and facilities.
The vote is part of a broader effort to modernize Dulles. Dulles already has a $7 billion capital plan under way, with work that includes a new concourse, an additional runway, a longer passenger train, and more parking. The proposal before the board would build on that work, bringing the full effort above $20 billion. Demolition of the two existing concourses, C and D, is set to begin in 2031, and the new regional concourse is expected to begin construction in 2039.
The authority has said the work will be phased to minimize disruption to travelers. The new $15.5 billion capital-budget increase would add to the existing $7 billion plan, with the combined program reaching more than $20 billion through the 2030s.
Travelers would see a larger main terminal, upgraded concourses, an extended automated train, and additional concourses built out fully.
For investors, municipal bonds are how projects like this get funded, and this proposal adds $14.2 billion in new debt.