A Response to Arguments in Opposition to Personal Rapid Transit

by J. Edward Anderson

August, 1999

Margaret Beegle talked to Steve Berg, who writes on transportation issues for the Minneapolis Star Tribune newspaper. He said that he was opposed to PRT, and when asked for reasons gave the following:

PRT would be more expensive per person than the automobile.

PRT would have an unsightly maze of overhead guideways.

PRT is anti-communitarian--it would raise individuals above groups.

PRT has not been tried anywhere.

PRT has been rejected elsewhere.

It is essential that we examine carefully all reasons given for opposition to any idea that we attempt to advance, and that of course applies to PRT. As a first general comment, Mr. Berg, there have been many systems called PRT most of which were not cost-effective, so it is necessary when criticizing PRT to state which PRT system is being criticized. For example, in April 1974 the Minnesota Legislature passed an Act directing the MTC to plan a transit system having small, automated vehicles operating on small guideways and capable of on-demand service and nonstop trips, which is a good description of PRT. In 1973, the Senate Transit Subcommittee conducted an extensive set of hearings to find the truth about transit options and took trips to investigate new automated transit systems. The system that most impressed them was The Aerospace Corporation PRT system. The MTC, on the other hand, being an advocate of large-vehicle, conventional fixed-guideway transit selected for their cost study the characteristics of a federally funded automated guideway transit in Morgantown, West Virginia, which was called PRT, although it used 20-passenger vehicles. The ratio of the cross sectional area of the Morgantown guideway to the Aerospace guideway was about 8.7, and its system cost was greater by about the same ratio. Since then, people in the Twin Cities Area have been given the impression that PRT cost is to high to be feasible. When one hears a comment about PRT, it is therefore necessary to inquire as to which PRT system is referenced . The following comments on the five points take as representative of PRT the system developed beginning at the University of Minnesota and called Taxi 2000. This PRT system has won three international competitions, one at SeaTac Airport, one sponsored by the Chicago RTA and one sponsored by The Sky Loop Committee of the Cincinnati Area. No other PRT system has won any similar competitions. More information can be found on www.taxi2000.com .

Now to respond to the above five points:

The average total cost per vehicle-mile of the automobile is about 50 cents, whereas the total cost per vehicle-mile of Taxi 2000 PRT is about 40 cents, of which about 15 cents is for operation and maintenance. The cost per passenger-mile for Taxi 2000 is about the same. The corresponding cost for light rail systems ranges from about $2 to $6 per passenger-mile.

Use of exclusive guideways away from the street system is essential if congestion is to be reduced and a high level of safety is to be attained. Surface level light rail generally increases congestion because the space taken up does not carry as many people per hour as the automobiles it displaces, and according to federal data these systems kill about three times as many people per passenger-mile as bus systems. Since underground systems are generally very expensive, maximum attention has had to be placed on making an elevated system as visually attractive as possible and as low a noise generator as possible. The Taxi 2000 vehicles run on smooth rubber tires on smooth rails so the noise level is very low. The degree to which visual attractiveness have been achieved in the Taxi 2000 is in the eye of the beholder. Two of the country's leading landscape architects, Professor Phil Lewis of the University of Wisconsin and Professor Charles Harris of Harvard University have gotten so enthusiastic about the Taxi 2000 design that they have spent a considerable amount of time promoting it. A leading Chicago sculptor John David Mooney has referred to Taxi 2000 as "moving sculpture," an element that, when one realizes what it does for the community, enhances the urban scene. In many, but certainly not all, applications in which we have been involved, visual impact has simply not been an issue. For a recent example, see the SkyLoop website.

This argument has occasionally been raised by advocates of conventional bus and rail transit, which has been loosing steadily to the automobile and now attracts in the United States less than three percent of the urban trips. According to a 1990 study by the Metropolitan Council the rush-period average auto occupancy is 1.08 and the daily average is 1.2, which shows that the vast majority of the trips taken in a metropolitan area are taken by one person traveling alone from and to a place and at a time of his or her own choosing. PRT will enable such trips to be taken in greater comfort and safety than in an automobile, and with trip times less in congested cities than in an automobile. On the other hand, regular use of urban bus or rail systems requires an extra travel time commitment of about an hour a day. PRT will be "communitarian" because it permits people arrive more easily at their destinations, where socialization takes place. Anyone who has ridden the New York subway will be familiar with how little interaction there is between people who are simply anxious to get to their destinations.

Notwithstanding its large size, the Morgantown so-called PRT system has been in regular operation since the mid 1970's and is still in operation today with a recently refurbished Boeing control system. The lack of trials beyond that occurred because lobbies for conventional transit were effective in killing the federal High-Capacity PRT program in September 1974. PRT was too much competition for these conventional systems and thus had to be killed. Having seen that, private investors lost interest. Transit agencies generally look to federal leadership, and indeed the rest of the world looks to the United States for leadership. The lack of federal support has made the emergence of PRT very difficult.

Saying that PRT has not been tried is a little like breaking a dog's leg and then remarking on how difficult it is for the dog to walk. The Chicago Regional Transportation Authority broke the logjam in 1990 with their announcement of a program to develop PRT. Unfortunately, however, the bureaucratic process coupled with a non-cost-conscious military-engineering-system developer combined to build a system to large and too expensive to be practical. That has unfortunately delayed acceptance, but the existence of the RTA program has resulted in PRT work in Sweden, Norway, England, Korea, Japan, Australia, Canada and in several locations in the U. S., and we are aware of PRT planning efforts in a half dozen other countries.

Has PRT been rejected elsewhere? Here we must ask Mr. Berg for examples of specific cities and specific studies before serious comment on this objection is possible. We are aware of many cities where there has been great enthusiasm for PRT, unfortunately dampened by the problem of acquiring a truly cost-effective system. Such a system is Taxi 2000, and we are very enthusiastic about the warm reception we have been receiving in more places than we can handle. Getting PRT going in the face of government opposition due to the conventional-transit lobby and then government indifference has been a challenging problem, but one that will soon be overcome.


Last modified: August 22, 1999