High Quality Content by WIKIPEDIA articles! The Los Angeles County Metro Rail system, also known simply as Metro Rail, is a combined rapid transit and light rail system in Los Angeles County, California, operated by the Los Angeles County Metropolitan Transportation Authority (LACMTA). The system is composed of two rapid transit lines and four light rail lines that run on 87.7 miles (141.1 km) of track. As of March 2012, Los Angeles County Metro Rail serves an average of 323,870 passengers each weekday, 192,943 each Saturday, and 146,646 each Sunday. Metro Rail is one of the largest rapid transit and light rail systems in the United States by ridership.