What types of tags are used to track railcars and alert passengers how long it will be before a train arrives?
Systems that determine the locations of trains can utilize either or active (battery-powered) or passive tags. Hamburger Hochbahn, the operator of the commuter rail system in Hamburg, Germany, has been employing passive RFID tags to identify railcars and the direction they are moving (see Hamburg's Rail Operator Continues to Roll Out RFID). And Spoornet, a South African railway operator, is using passive ultrahigh-frequency (UHF) tags (see South African Railroad Switches to Passive RFID). This involves placing a reader on the tracks, or near the side of the tracks, and tagging either under the train car or on the side of the train, and then reading the tag from within 25 feet or so.
In North America, almost all freight cars are tagged with active RFID transponders, which communicate at longer range. The main purpose is to identify cars so they can be efficiently located and switched to different tracks, but the same application could be used for identifying approaching passenger trains and alerting commuters as to when a train will arrive. Passive tags are less expensive, because they have no battery, which is one reason some rail operators have gone this route, so to speak.
Railways are also using RFID to collect fares (see Chinese Railway Switching to RFID Transit Cards) and Norway Railroad to Roll Out E-Tickets). In 2008, Deutsche Bahn, Germany's national rail company, and German-based cell-phone service provider Vodafone, introduced Touch & Travel, a system that works with RFID-enabled signs and cell phones to eliminate paper tickets in the country's extensive public-transportation network (see Deutsche Bahn Launches Touch & Travel)
—Mark Roberti, Editor, RFID Journal
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