does the above mentioned organisation maintain any other means of transport?
Yes, Metrobus.
Washington Metropolitan Area Transit Authority
Metrobus' fleet consists of 1,505 buses covering an area of in Washington, D.C., Maryland, and Virginia. There are 269 bus routes serving 11,129 stops, including 2,554 bus shelters. Metrobus had 130.8 million trips in 2016. On a typical weekday, it provides more than 400,000 trips.

The route numbering represents its region of operation. To differ the regions numbering system, letters for Maryland routes appear before the route number and the ones for Virginia routes appear after it. For example, A12 serves Maryland, and 17M serves Virginia.
how did district of columbia get its name UNANSWERABLE is it known by any other name? D.C. or Washington. what is it most famous for? The capital city of the United States of America. are criminal activities frequent here? A 2010 study found that 5% percent of city blocks accounted for more than 25% of the district's total crimes. what are some of the common means of public transport here? Metro and airport, to name a few. who maintains the former? The Washington Metropolitan Area Transit Authority. when did the above mentioned rail begin its operations here? Mid-19th century. have they faced any mishaps? Yes, on June 22, 2009, two Metrorail trains collided between the Takoma and Fort Totten Metro stations, killing nine.
wiki:12199394
Washington Metropolitan Area Transit Authority [SEP] Metrobus
Metrobus' fleet consists of 1,505 buses covering an area of in Washington, D.C., Maryland, and Virginia. There are 269 bus routes serving 11,129 stops, including 2,554 bus shelters. Metrobus had 130.8 million trips in 2016. On a typical weekday, it provides more than 400,000 trips. The route numbering represents its region of operation. To differ the regions numbering system, letters for Maryland routes appear before the route number and the ones for Virginia routes appear after it. For example, A12 serves Maryland, and 17M serves Virginia.