Washington Metropolitan Area Transit Authority officials released new expansion proposals Monday, including plans for a new Georgetown stop and an added tunnel between D.C. and Virginia.

Implementation of one of the six new proposals, designed to deal with capacity increase on the transportation system, could cost anywhere from nothing to about $50 billion and could take up to 10 to 20 years to complete, according to officials.

Metro recently completed the Silver Line, which cost $3 billion and took nearly 60 years to come to fruition. 

Metro is also headed into its next financial year with a $750 million operating deficit. Officials said the possible expansions, however, are necessary to increase system reliability.

“Running three lines through one tunnel and set of tracks creates challenges for Metro and our customers, including crowding during peak periods, service reliability issues, a lack of operational flexibility, and threats to long-term sustainability,” officials said in a presentation.