III POTENTIAL ADVANTAGES

A. Efficient Use of Rights-of Way

First and primarily, it must satisfy the requirement of efficiency. It must provide an increased capacity for a given right-of-way by a significant factor. Now, what is a significant factor? A simple calculation [1] suggests a theoretical maximum capacity approaching 17,000 vehicles per hour. This is sufficient to accommodate the maximum peak one-way traffic in Caltrans District 7 (Los Angeles and environs). Apropos of perhaps nothing (we would never consider less than one line in each direction), it is sufficient to accommodate the peak traffic in both directions for the overwhelming majority of the freeway system.[2]

The full utilization of the guideway will depend critically on the way demand builds up, and the method of control. Traditionally, demand has built up along a single line, growing larger towards a central location, usually referred to as the central business district (CBD). Under this model, control is relatively straightforward. The traffic simply is allowed to grow toward saturation. Under these conditions, at specific locations the probability of reaching something very close to the theoretical capacity would be high.

It is anticipated that this traditional model may grow increasingly less predictive – that is, there will likely be considerably more suburb-to-suburb travel. Thus, it will become increasingly more important to develop a thorough understanding of system requirements, both present and future. This is true, independent of whatever means of transit we adopt. As demand grows, we must insure that the system remains balanced and provides equality of access. We must not allow parts of the system to become clogged to the extent it tends to starve others. Thus some restriction on access, or quotas, which serve to limit maximum utilization at specific locations are probably inevitable. In subsequent discussions, we suggest a peak capacity of something in the order of 15,000 may be realistically achieved.

Accordingly, a goal of full utilization is unrealistic – certainly as a goal throughout the entire system. Nevertheless consideration of maximum peak capacity does serve to illustrate the advantage of high-speed, close-packet operation

But to answer the question: the system must provide an increased capacity for a given right-of-way by a significant factor. Typically, a freeway lane is thought to be able to accommodate a peak capacity slightly in excess 2000 vehicles per hour. Thus, a peak capacity of 15 thousand vehicles per hour, or a capacity enhanced by a factor of some 5 to 7, must be considered significant.

B. Reduced Real Estate and Other Costs

We assume that, at least initially, the guideway-based system would be installed in conjunction with existing freeways. The traffic patterns are already established, and in many instances a median exists which could provide the right-of-way. Moreover, if it were necessary to encroach on the freeway itself, the additional capacity of the rail line would more than compensate for the lost capacity of the encroached lane. Further, we assume that the bulk of the cost would represent itself in acquisition, construction and maintenance of the right-of-way. It is not an unreasonable assumption that the cost of installing a guideway would be in the same order as a freeway lane. Thus, assuming the increased efficiency, fewer guideways would be required than freeway lanes. Fewer lines, or lanes, represent less cost.

The other major cost is that of the carrier itself. No detailed estimate of this is practicable prior to the selection of an actual design. Nevertheless, it may be useful to compare our requirements to those of a medium-duty commercially available truck. The basic mechanical components are a frame and vehicle platform, electric motor and driveline, wheels, and brakes. No automatic transmission; no cab or other coachwork; no passenger amenities; no periodic model changes; and no marketing, advertising or dealer costs. We do, of course, have to add a computer, communications, and sensor electronics; but the cost of these are dropping dramatically. Thus it is a reasonable assumption that the cost would be a fraction of that of the truck; perhaps in the order of ten thousand dollars.

To gain some perspective, consider the carrier density required for the maximum theoretical capacity contemplated by the previous example. Under our assumptions the cost[3] of a "maximum density mile" of carriers would be something in the order of two million dollars, possibly less. The cost of one mile of urban freeway of comparable capacity is typically several times this. It hardly needs to be said that it would not be necessary to acquire the maximum amount of carriers until the demand was manifest.

C, Safety and Accident Reduction

Moreover with each carrier provided with redundant safety controls (thus removing human frailty); it is anticipated that the accident toll could be reduced dramatically from that presently experienced on the freeway. Not only is this hugely desirable from a humanitarian standpoint, it also reduces property and productivity losses. This should manifest itself in reduced insurance rates.

D. Favorable Environment Impact

Assuming all this, several additional advantages present themselves. We propose that the energy for propulsion be electric and while being transported, the automobile's engine is turned off. Thus for the largest part of the commute, automobile exhaust is eliminated. Of course the electrical energy must be generated, most probably with fossil fuels. Nevertheless, a central location facilitates both preventive measures and monitoring. Moreover, these plants can be removed from sensitive environmental areas (as in the Los Angeles basin).

The advantages continue. We assume initially that the transported vehicles would be essentially what is presently on the freeway. However, with appropriate financial incentives we might encourage people in the use of electric vehicles and make the entire journey non-polluting. The objection to electric cars is a limited range. If, however, we provide an on-board charging facility we effectively extend that range enormously. All this with current technology.

In a like vein, we could encourage car pooling, and consequent energy reduction, by offering similar economic incentives. In addition to economic incentives, priority of access could be granted during periods of heavy demand.

In addition to reducing pollution, another environmental advantage might also be realized. A high system speed in conjunction with a more pleasing experience will combine to allow consideration of longer commutes (in terms of distance, not necessarily in time). This in turn would provide regional planners with more flexibility to maintain green space in and around developing communities.

E. Fuel Conservation

While this approach represents a massive shift in energy distribution, we submit that the total energy required is reduced. Clearly steel on steel (or similar hard materials) requires less energy than pneumatic tires on roadway. In addition, the "drafting" occasioned by close-packed, constant-velocity vehicles certainly requires less energy than the sum of each proceeding individually. As much as 30 percent in a USC study.[4] Energy recovery with dynamic braking is also possible.

In addition to the economy of scale provided by large central plant(s), other advantages obtain. For instance these plants would not be limited to specific types of fuel, or the continued use of a specified fuel. The most economical for the moment would be chosen. Certainly the more abundant natural gas, or even coal can be considered. All would contribute to a lessening of our dependence on imported petroleum.

F. Revenue Source

An important advantage stems from the fact that while being transported the occupant(s) really have nothing to do. It is a stress-free environment freeing the occupants to pursue any number of other activities. A busy executive can organize his day, read reports, talk on his cell phone, whatever.

Accordingly, not only are the commuter's direct fuel and maintenance costs greatly reduced, but also a lengthy commute is transformed from a horror to comparative pleasure. This has economic value - one can charge for this. As there is already a need to communicate with the carrier (to tell it where to go) it seems reasonable to extend this to a system for collecting toll data. Regular commuters might be billed monthly with occasional users using some sort of toll box. Thus the system could be made to be either partially or completely self-supporting. It is not without possibility that the system could be financed with some sort of revenue bonds – transferring the financial burden from taxpayers in general, to those whom specifically benefit.

G. Summary

A guideway-based car-ferry system may offer significant advantages to both individual commuters and society as a whole, with (aside from the initial cost) few disadvantages. It maintains the flexibility of individual vehicles so dear to the hearts of commuters (particularly in southern California), combined with a comparatively effortless commute. It provides for efficient utilization of rights-of-way while at the same time significantly reducing automobile pollution. Further, it can dramatically reduce the carnage on the freeways, with a special emphasis on the elimination of “road rage”.

Only a more detailed and thorough study will provide the basis for an informed and quantified opinion. Our purpose here is not to urge immediate adoption. Rather, it is to acquaint the reader with the many advantages inherent in this general approach. And, for those in a position to do so, urge that funds be made available for a comprehensive examination of this prospect, by academics and transit experts alike. We suggest this, if for no other reason than to stimulate thinking beyond the present flawed policies of more freeways and light-rail.

^[1] Consider a system of carriers, each 18 feet long, 20 carriers to a packet, with 150 feet separation between packets. If the system speed is 120 feet per second (81.82 MPH), a packet passes a given point at the rate of one every 4.25 seconds; or 16,941 vehicles per hour.

[2] All data are from 1998 Traffic Volumes, State of California, Business, Housing and Transportation Agency, Department of Transportation, June 1999. The maximum peak one-way traffic of 13,511 vehicles per hour appears to be on Route 5 at milepost 44.5 (near Castaic). For the most part, this number seldom exceeds 10,000. In comparison, the maximum two-way traffic is 22,400 VPH on the Ventura Freeway at the intersection with the 405.

[3]In footnote 5, we postulated 18 feet carriers in packets of 20, with a minimum packet separation of 150 feet. This provides a density factor of slightly over 70 percent, corresponding to 207 carriers per mile. Thus, if the cost of each carrier were $10,000, the total carrier cost of a “maximum density mile” is $2,070,000.