maintenance contract through the $2 million savings the LEDs will provide each year. See also List of railroads in Washington, D.C. Washington Metro List of United States railroads Metrobus (Washington, D.C.) MetroAccess SmarTrip – payment system for use of Metro transportation and Metro parking References Bibliography External links Library holdings of books, maps, etc, relating to the Washington Metropolitan Area Transit Authority (WMATA) Guide To The Washington Metropolitan Area Transit Authority: Metro History Project Collection, 1930-1984, Special Collections Research Center, Estelle and Melvin Gelman Library, The George Washington University United States interstate agencies Underground rapid transit in the United States Transit authorities with natural gas buses 1967 establishments in Washington, D.C.