The P is for pipe dream

Personal Rapid Transit (PRT) is a name not well known outside of transportation circles, and for good reason: its deployment is extremely limited and its concept has substantial flaws.

PRT advocates trumpet its benefits as if it is the best solution in transportation, able to replace both inefficient cars and cumbersome mass transit. This is often paired with theories about evil car and mass transit manufacturers blocking PRT, which earns its proponents the name 'PRTists'. In reality, PRT does have limited applications, but it is not a solution for city transportation systems.

Let's look at the basic idea of PRT. Small, computer-controlled cars holding anywhere from two to six passengers run on elevated tracks to the passenger's desired station, without stopping at any other stations along the way. In theory, empty cars will always be waiting for you at a station, so you never have to wait. It mirrors automobiles in its on-demand nature and small capacity and it mirrors some transit in its use of stations and electrified vehicles.

It's the best of both worlds, is what proponents—like Citizens for Personal Rapid Transit who had a booth at the Living Green Expo—would have you believe. A system in Minneapolis has even been proposed by now-former Minneapolis Councilmember Dean Zimmerman.

The problems, however, are significant. Elevated tracks often degrade any property beneath them, as well as the urban landscape in general. As Yonah Freemark of the Transport Politic points out, PRT and its small cars don't come close to matching the capacity of buses or light rail. If you ride the Hiawatha LRT during rush hour, try to imagine every individual (only occasionally more than one person) in their own car, and you can see the problem. They don't work along dense corridors.

Some PRT advocates claim the system to only be supplemental to other transit, serving as a 'last mile' solution. That 'last mile' is often through lower density areas, and the cost of elevated tracks and stations is hardly justified by low density corridors.

There are two PRT systems in operation in the world today. One is in Morgantown, designed to link the University of West Virginia's Morgantown campuses, and the other is in the new city of Masdar in the UAE. The operating systems are limited, with two passenger stations in Masdar, and five stations in Morgantown. A third system very close to completion is in London Heathrow Airport. These represent the range of applications of PRT. It is useful in places that have a constant, but low-capacity need for transportation between limited stations. Large shopping centers and corporate campuses fit this bill as well.

The only cities it works in, as Freemark states, are new cities where it can be incorporated into an urban landscape that is literally being built from scratch.

As Christopher Mims points out in a Txchnologist article, the real future of anything resembling PRT is autonomous cars, which use existing infrastructure and potentially provide more benefits than PRT. Google is developing autonomous cars, which we recently wrote about, so that future may not be too far away. For now in Minnesota, we should continue focusing on maintaining our infrastructure and funding our current transportation systems.

Photo credit: Skyburn, Wikimedia Commons