I think the new beltway expansion will be built right on top of the existing beltway. They can't expand left or right, so the only way left to go is up. Make prefab sections somewhere else. Drag them to the site and attach them erector set style. The lower road will be in constant shade which will be somewhat depressing on winter days. The construction process will jam up an already horrible situation. But once it's finished, things should go along smoothly. Just like the expansion of the Wilson bridge years ago.If I may ...
I imaging at some point, another area of 10 square miles, of vacant land, somewhere in the good 'ol US of A, will be identified as the next location for a new said District, encompassing, that will be restricted for the sole purpose of Federal use, Federal Buildings and Federal employee housing only. Once a Federal employees retires, they would be required to move out. Commit a crime, forced to move out. Kinda like living on an Army base in the barracks, but different.