A small unit within the Metropolitan Transportation Authority in Los Angeles has been formed to target sexual predators riding public transportation. The new Los Angles unit has designated special plain-clothes officers to ride on city buses and on the subway system specifically for the purpose of apprehending sex crimes offenders. Sexual assault on public transportation is common, and the crimes often go unreported. Offenders often target public transportation because of the high concentration of people, the anonymity of the crowd, and the quick escape possibilities. Similar deterrence and apprehension units have been implemented on public transit systems in both New York and Tokyo.