Personal Rapid Transit

Personal rapid transit (PRT) systems are a subset of automated guideway transit (AGT) systems, at the smallest end of the capacity spectrum. Recent plans for PRT systems have sometimes used the terms podcar or pod. While typical people movers, another form of automated transit system, are often similar in capacity to traditional buses or train cars, PRT systems transport either individuals or small groups of up to six people. The vehicles are considerably smaller than those used on other automated transit systems, no more than 20 feet long and 8 feet wide, with a maximum travel speed of 20 miles per hour. Typically, PRT systems are used for direct routes from one point to the other, with no stops along the way. PRT systems are sometimes compared to automated taxis, but because they follow a guideway, they lack the flexibility of an automobile.

PRT systems are driverless, traveling along an aerial or underground guideway system. Because payroll is the biggest annual expense in transit systems, automated systems reduce costs of transit and make it financially feasible to offer free transit in certain situations. For instance, automated systems are used in many airports, which assists in airport layout by reducing the time it takes for passengers to arrive at a given terminal. However, because they carry only a few passengers at a time, PRTs can offer more flexible types of service.

After years of attempts at developing PRT systems, most of which were failures, the Advanced Transit Association (ATA) in 1988 created a set of guidelines defining what is meant by PRT, as opposed to other transit systems. PRT systems are fully automated and operate on a dedicated guideway, either underground, at ground level, or aboveground. They are small vehicles available 24 hours a day for one to six passengers. A PRT vehicle is able to access all the guideways and stations on a fully coupled network. Service is direct, without transfers or stops. Service is available on demand. Ideally, a PRT system offers the same access to the elderly and disabled as other transit systems do; though this is not specified in the ATA guidelines, it can be inferred from the Americans with Disabilities Act.

PRTs were one of the many transportation concepts that developed in the tech and engineering boom that followed World War II, in part as a result of the amount of resources and attention devoted to training engineers in the war years and subsequently in the Cold War, and in part because of the baby boom, a subsequent housing boom, and the changing layout of the country. The federal government began funding studies to develop automated transit systems, including PRTs, in the 1960s, and in the 1970s numerous transit possibilities competed for attention, funding, and planning committee preference, including PRTs, monorails, refinements to existing subway and bus systems, automated walkways, and other solutions to increasingly urban and suburban American life. The rapid rise of car ownership and driving in the same period was in some part a response to the delays that prevented transit solutions from being implemented earlier, and in part exacerbated those delays by reducing demand for public transit. As the relatively affluent middle class expanded, two-car households became more common, contributing to the tendency of suburb developers to leave transit needs barely addressed except for the question of how to get children to school.

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