BTTT for later reading
Complete waste of money. BWI is already served by commuter trains and Amtrak. Baltimore and DC are already connected by those, also. In fact there are two commuter rail lines between the cities, which could be upgraded for faster and more frequent service for about 1/40th of the cost.
Zero federal dollars to such duplicative waste.
I wouldn't count on that Metro to Dulles ever coming on line, either. The Metro tunnel from VA to DC is already running at max capacity and it can't handle additional traffic. So they will not only have to dig up a huge swath of Tyson's Corner, but they will also have to dig another tunnel to get it to happen.
Amtrak and MARC trains already run from New Carrollton to BWI. MARC runs from Greenbelt to BWI. With the "National Agricultural Research Center", "Patuxent Reseach Center", and Fort Meade, there is almost no population between Greenbelt and BWI. Why in the world do we need a Metro line going through the woods?