those carrying packages or in case of an emergency, and a more open feel for passengers. On buses, proof-of-payment saves drivers the time needed to collect fares, and makes it possible for all doors to be used for boarding. Validated tickets can double as transfers between lines. Disadvantages include potentially higher rate of fare evasion, reduced security on station platforms when no barrier is used, increased potential of racial profiling and other unequal enforcement as "likely fare evaders" are targeted, and regularly exposing passengers to unpleasant confrontational situations when a rider without the proper proof is detained and removed from the vehicle. Visitors unfamiliar with a system's validation requirements who innocently misunderstand the rules are especially likely to get into trouble. Worldwide uses Proof-of-payment is popular in Germany, where it was widely introduced during the labor shortages resulting from the Economic Miracle of the 1960s. It has also been adopted in Eastern Europe and Canada and has made some inroads in newer systems in the United States. The first use of the term "POP" or "Proof of Payment" on a rail line in North America is believed to have been in Edmonton in 1980. Since then, many new light rail, streetcar, and bus rapid transit systems have adopted the procedure, mainly to speed up boarding by avoiding the hassles of crowding at doors to pay fares at a farebox beside the driver as is common practice on traditional buses. San Francisco's MUNI system became the first North American system-wide adopter of the proof-of-payment system on July 1, 2012 across its buses, light rail and heritage streetcars, with the exception of cable cars, allowing boarding on all the available doors. Notes External links TCRP Report 80: A Toolkit for Self-Service, Barrier-Free Fare Collection (PDF) Public transport fare collection