DEBATE, DEBATE and No QuadMode PRT Systems


Gary Webber

The problem with the PRT debate is that different camps think that there is a scientific basis by which a determination can be made to select the best mode or the best system. The result is endless debate and no PRT. Science has value but the market has more.

What is needed is a design and build competition wherein various ideas or "modules" can be tested and evaluated in a real time demonstration/competition. Ultimately, the marketplace, and not studies and debate, will determine the best system. As an example of modular evolution one can observe the vast improvements in jet engine design. They are a modular component of airplanes.

Modular Design:

Design of a PRT/QuadMode solution should be modular, ie: a multitude of connectable parts that can accommodate a variety of solutions. One of the flaws with fixed rail is that it is a monolithic system, not amenable to evolution and advancement. PRT/ QuadMode should avoid the same trap. What was designed in the 1900's dictates and limits evolution and improvement of rail systems. On the other hand, the automobile has evolved and vastly improved because components can be improved and interchanged.

PRT/QuadMode Components:

The basic components of a PRT/QuadMode system may include the following:

The supporting pole footing or foundation

The supporting poles

Structural spans, like Lockheed Martins prefabricated fiberglass bridges

Space contained within the Glideway to accommodate optional propulsion and guidance.

Various "Glideway" levitation methods, i.e.: super magnet, air or mag lev

Various "Glideway" propulsion methods, ie: linear

Elevators for access to the "Glideway" or "on ramps"

Switching options

And, small vehicles, of a multitude of designs but of standard configuration/dimensions

QuadMode envisions the vehicle operating on the "Glideway" surface. (Although the EGS website depicts suspended vehicles)


QuadMode refers to the four functioning options available to PRT vehicles:

Normal 40 mph street travel, ie: conventional

IVHS low speed street travel, ie: smart highways

IVHS 60 mph "Glideway" travel, using vehicle wheels for levitation

Propelled by vehicle power, or

Propelled by the "Glideway" system; ie: linear propulsion

Air or super-magnet levitated high speed travel on the Glideway

Propelled by the "Glideway" system, ie: linear

The marketplace will determine which mode is most logical and preferable.

Option No. 3 could easily be built now. In time, when more sophisticated levitated and propelled systems were perfected, and where suitable, they could simply be incorporated into the system, ie: mode # 3 is built to accommodate later incorporation of mode # 4.

Switching and Propulsion:

The key to high speed, levitated Glideway travel is switching. Headway and vehicle speed dictate system capacity. System capacity determines economic viability.

The WebbCo proposal contemplates a system that will propel and switch the vehicle in both a wheeled mode and a levitated mode. It is intended to operate at almost zero headway at high speed. Switching is magnetic, ie: no moving parts. The switch is contained within the "Glideway". This system was tested extensively in the ‘70’s in Los Angeles. Go to to view the switch design and other attributes of the system.


Preliminary economic projections indicate a "QuadMode Glideway" system that would earn an average annual net profit after all operating costs equal to about 30% of total capital cost. Taxpayers would no longer be saddled with transportation related taxes. Toll rate for use of "QuadMode Glideways" are priced 20% below the cost of operating conventional vehicles, not considering the vast subsidies for auto travel.

"QuadMode Glideway" 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.

Define the overall "modular" components and their interrelationship.

Identify prospective vendors for each component and then

Undertake a design and build competition.

Evaluate each component/each proposed solution and select the best module

Assemble the final system and test


The "Glideway" would be configured so that a multitude of Levitation and propulsion options could be incorporated and tested. An unidentified Bechtel engineer has said 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.


The marketplace should determine the mode and the system. All that is required is that design be modular. The rest will unfold very naturally. The next step is to organize a design and build competition.


Last modified: September 24, 2001