High Quality Content by WIKIPEDIA articles! The Purple Line, previously designated as the Bi-County Transitway, is a proposed 16-mile (25 km) transit line to link the Red, Green and Orange lines of the Washington Metro transportation system, in the Maryland suburbs of Washington, D.C. The project is currently being administered by the Maryland Transit Administration (MTA). On October 7, 2011 the proposed light rail line received Federal Transit Administration approval to enter the detailed engineering phase which, according to the Washington Post, is "a significant step forward in its decades-long trek toward construction."