Reliability Of Fare Collection Hardware In Subways

Measurements of failures in recently improved coin acceptors and bill validators in automatic fare collection (AFC) equipment at representative Bay Area Rapid Transit District (BART) stations in San Francisco reveals a tenfold improvement in reliability when compared with earlier units. The mean number of transactions per hard failure for the new bill validators is around 18,000 and for coin acceptors it is about 27,000; for soft failures it is around 500. The estimates of hard failure reliabilities are based on data in BART's data base system for Montgomery and Lafayette stations, for the interval February 1 - April 30, 1982. The soft failure count is based on two days of on-site measurements at these stations. "Hard" failures are unscheduled equipment failures repaired by trained technicians and documented. "Soft" failures are undocumented non-mechanical failures repaired by station agents. Certain soft failures are caused by interactions of patrons with equipment. For example, some failures depend on whether the patron is left-banded or right-handed. Reliabilities of gate sub-system components in the San Francisco Metro-Municipal Railway System ("MUNI-METRO") are summarized for November 1981. The mean number of transactions per failure for ticket and transfer jams are respectively, 20,685 and 2,000. New reliability measures to replace MTBF, such as number of patron coins deposited per failure, are used. The number of failures are proportional to the number of patrons using the equipment but increase at a nonlinear rate for larger numbers of passenger traffic. The influence of preventive maintenance on reliability is also quantified. It can double reliability.