Southern Maryland Rapid Transit
Southern Maryland Rapid Transit, abbreviated as SMRT, is a proposed mass transit line along the Maryland Route 5 and U.S. Route 301 highway corridors in between Washington, D.C., and Waldorf, Maryland. The project would link the heavily populated suburbs of northwestern Southern Maryland with Washington via a direct transit connection to the Washington Metro at Branch Avenue station.
Source: Wikipedia — Southern Maryland Rapid Transit (CC BY-SA 4.0)