A Quadmode Modular Personal Rapid Transit Concept

The problem with the PRT debate is that different camps think that there is a scientific basis available that can be used to determine the best mode. There is not any scientific basis that will accommodate all the variables that will lead to the identification of a proper selection. The answer is simple; the marketplace can and should determine the best technological solution.

Modular Design:

It is essential that the design of a PRT solution be modular, i.e.: consist of a multitude of connectable parts that can accommodate a variety of solutions or evolution's of the whole system. One of the flaws with fixed rail is that it is a monolithic system, not amenable to evolution of modular parts. What was designed in the 1900's dictates and limits evolution and improvement of its systems. On the other hand, the automobile has evolved and has been vastly improved because its components can be interchanged and improved.

Therefore, a modular PRT solution is needed that can incorporate components that exhibit a superior ability to perform particular functions.

PRT Components:

The basic components of a PRT system include the following:

The supporting pole footing or foundation

The supporting poles

Structural spans, like Lockheed Martin's prefabricated fiberglass bridge

Space in the span to accommodate optional propulsion and physical guidance systems

Various "Glideway" levitation methods, e.g. air or maglev

Various "glideway" propulsion methods, e.g. linear motors

Elevators for access to the "Glideway"


Dedicated or independent small vehicles, of a multitude of designs but of a fairly standard configuration

This system envisions the vehicle operating on the "Glideway" surface. The modular design would allow any and all of the various alternative designs for propulsion and levitation to be integrated. Thus, the best would prove itself and would be incorporated into the system.

As new systems were developed, they could replace old ones and the "Modular Glideway" system would evolve and improve. In this way the marketplace will determine designs, not scientific studies that will be outdated by the time the system is built.


Quadmode refers to the four functional options available to PRT vehicles:

1. Normal low speed street travel or ITS low speed street travel

2. ITS low speed "Glideway" travel, supported by the vehicle's wheels

3. Propelled by vehicle power, or propelled by the "Glideway" system

4. Air or maglev levitated high speed travel on the Glideway

The marketplace will determine which mode is most logical and preferable. Option No. 3 could easily be built now, with almost no research required. In time, if more sophisticated levitated and propelled systems were perfected, they could simply be incorporated into the system.

Switching and Propulsion:

The key to high speed, levitated travel is the switching and propulsion system. WebbCo has designed a system that will propel and switch the PRT vehicle in both a wheeled mode and a levitated mode. It is intended to operate at almost zero headway at high speed and is entirely contained within the "Glideway" system. WebbCo would like to affiliate with an engineer to refine the design of the "Glideway Switching and Propulsion" device. (see e-mail address below)


Preliminary estimates project a "Glideway" system that would earn an average annual net profit after all operating costs equal to about 30% of the total capital cost. With "Glideways" taxpayers would no longer be saddled with transportation related taxes. The toll rate for using "Quadmode Glideways" is projected to be priced 33% below the cost of operating conventional vehicles, not considering the vast subsidies for auto travel.

"Glideways" is to be a private sector transportation solution. The opportunity for profit will motivate developers to solve problems and to compete. In time competition will reduce tolls and costs. Despite good intentions, public systems never seem to fulfill even a small portion of their claims.

Development Strategy:

The modular "Glideway" and "Quadmode" concept should be developed now. First, define the overall "modular" components and their interrelationship, then identify prospective vendors for each component and then undertake a design and build competition. This can be done in 18 months. The "Glideway" would be configured so that a multitude of levitation and propulsion options could be incorporated and tested. I have been told by an unidentified Bechtel engineer that the cost of this design and build may be less than $20 million. But, Bechtel isn't interested because the system is too economical.


Delivery of packages and products to congested commercial areas might be the first application. After refinement of the system and assurances of safety, PRT applications would be developed. Las Vegas might be the perfect test, except Las Vegas seems committed to monolithic, large systems and not real solutions.


WebbCo has developed a script for a video depicting "Quadmode Glideway"- "QG" transit. The "QG" system is to be overlaid on actual scenes of a City's congested environment. Possibly, a group of Cities could fund the $300,000 cost of this video. Movie makers might also use the "QG" depiction's in futuristic films. Or, CD ROM game developers might use "QG" as the theme of games and contests.

The result would be clear depiction of the ground transportation solution, i.e.: "QG", with faster door-to-door travel times from LA to San Francisco than airlines, with high speed city-to-city travel, and with greatly facilitated intercity travel.


The marketplace should determine the mode and the system. All that is required is that design be modular. The rest will unfold very naturally. QUADMODE, a PRT plan operating on modular GLIDEWAYS

For additional information, contact Gary Webber at WebbCo, Mt Baldy, CA 91759-0820


Last modified: September 22, 1998