V   THE ARGUMENT FOR PALLETS

 

There is considerable controversy over the question of so called true dualmode versus palleted dualmode. It should be noted that the use of the term pallet is an inclusive one; it includes such terms as carrier, car-ferry, and the like. The distinction between true dualmode and the palleted variant is that in the former, the guideway vehicle is also fully capable of operating on the street, while with the latter, the street vehicle is carried about on a “pallet”.  The arguments are not totally one way.  Nevertheless, on balance we favor pallets – for initial installations, at a minimum.  In other sections of this report, we refer to carriers.  For our purposes pallets and carriers are the same.  However, since the literature usually refers to this question as palleted vs. true dualmode, we will defer and use the term pallet in this section only. 

 

 

A. Minimum Economic Viability

 

The most prevalent argument used to advance palleted dualmode is the so-called "chicken and egg" problem. Which comes first, the guideway infrastructure or qualified users.   This argument is primarily economic.  It is assumed in true dualmode, the cost of the vehicle would be borne by the individual.[1]  Thus the question is how extensive the guideway system would have to be before a significant number of would choose to pay out the $30,000 or more to purchase a guideway compatible vehicle.  It is our view that it would take an extensive system before a sufficient number would be willing to do so.  This question is further complicated by the lack of any standard.  Early purchasers would have no assurance that subsequent standards would be compatible.  We will have more to say on this issue later.

 

Judging by the pace of freeway construction, it might take some time, perhaps several years or possibly a decade for an extensive system.  A delay of anything like this would render any system both financially and politically untenable.

 

Moreover, this economic divide might appear to many as undemocratic.  Initially, only the wealthy could, or would, afford the expense for the limited value afforded by a few miles of an initial installation.  

 

On the other hand, a short stretch of a dualmode system that required little or no modification to one’s existing vehicle would attract instant use.  This would be of particular value if it were constructed at a location of high traffic density.  In effect, this would enable those whose destination were beyond to bypass the bottleneck.  The consequent reduction of freeway traffic would similarly benefit the remaining users.  It is our strongly held opinion that the system must be available to all from the beginning.         

 

 

B.     Unified Control of the System

 

While we regard these economic arguments as valid and substantial, there are additional issues that may be even more important.  There is no more important interface than that required between the general system and the vehicles, whether pallet or not. It is essential that all vehicles be in good order. There can be no ambiguity about the responsibility for assuring this.  For a system of this type, safety can not be held hostage to, more or less, voluntary compliance.  California has a legal requirement for mandatory automobile insurance; yet many do not posses it.     

 

It has been suggested that as true dualmode vehicles enter the system, the good order can be insured by an instant test of some sort.  Perhaps later, but for the present we believe that only thorough and frequent, off-line, non-revenue testing of all vehicles using the system will insure the integrity of the system. This can only be accomplished if the system is in complete control of its own destiny i.e., directly controls all the operational pieces. If it is ever to turn over partial control, this can be only after extensive development and testing in a real operational environment. There is simply no margin here for  "oops".

 

Divided responsibility (even the appearance of it) invites disputes and thus delay, and quite possibly a less than optimum system.  As problems develop (as inevitably they will) a single agency must have both the authority and the responsibility for instituting solutions in a timely manner, with a minimum of jurisdictional squabble.  This can only be effected with pallets.

 

 

C.  Several Approaches Required

 

Hopkins[2] of the Volpe Lab has been quoted extensively on this subject, but we believe none more to the point than when he wrote, "Without very limited small-scale revenue-producing applications to establish credibility, there doesn't seem much likelihood of getting anyone to take a really large-scale program seriously."[3]

 

Considering the novelty and scale of this undertaking, We believe it prudent, more likely essential, to consider more than a single exploratory project. To encourage and facilitate an optimum outcome, we should impose an absolute minimum of standards or other impedimenta to future development. In this, we refer only to system standards, certainly not safety standards.

 

Accordingly, it is imperative that as many users as possible actually use these systems as early and as frequently as practicable. To accommodate this, a minimum of special apparatus should be required of the user’s vehicle. It is also extremely desirable that many users have the opportunity to use multiple systems. In our view, only palleted dualmode has the flexibility that adequately satisfies all these requirements. Developers or local agencies must be free to provide the system thought to be best suited to the local need.  The requirements of the Sun Belt are not identical to those of the northeastern seaboard.

 

a.  An Optimum Approach Not Apparent  Nevertheless, there have been calls to come to­ gether and agree on a common operational standard. We believe this is shortsighted, or at best premature. Presently, several competing systems are being proposed; each with substantial differences, and in varying degrees of development. Absent any operating experience, and with the champions of each claiming superiority; how is one to decide to which should we pledge our enthusiasm.  It should be noted that the selection of a national guideway standard to accommodate a true dual mode vehicle would have the effect on locking-in that design as a standard in the same way the original standard gauge did to railroads.  There a few, these days, who would not have preferred a wider standard.

 

We have an obligation to study and learn from out mistakes.  We suggest that none of us, either individually or collectively, absent any operating experience, has the necessary knowledge or prescience to infallibility select the optimum technology for the mid twenty-first century. It is only after the experience of substantial revenue service, with more than just a single system that we can begin to make informed choices. It is only then that we can even begin to contemplate any national standards.

 

b. Pallets Do Not Hinder Development  Some have expressed the concern concerned that if an adequate pallet system is developed, this would inhibit the development of a true dualmode (and thus, by implication, a superior) system. Accordingly, we are urged to go directly to true dualmode. Moreover, this should be a national system.  The same arguments apply - the greater danger is in making any final decision absent empirical evidence of any kind.

 

We are not persuaded that the use of pallets somehow, inherently, compromises optimal development. It is almost always true that a design optimized for a single task is superior to one that must perform several. Moreover, aside from the unfortunate emergence of SUV’s, private vehicles, computers and communication equipment, and almost everything else tend to be smaller and more able in subsequent models.

 

Thus the design of a true dualmode vehicle, should we choose, in time, to do so would benefit by earlier experience with pallets. We see little reason that the advantages of a specific guideway, the superiority of linear versus on-board motors, or even the value of magnetic suspension versus the use of rail, cannot be profitably explored with pallets.

 

 

D.  Number of Pallets Needed

 

Looking to the future, we would disagree mildly with the assertion[4] that palleted dualmode cars ". . . are more expensive and less elegant than pure dualmode."  Elegance, like beauty, is in the eye of the beholder; but expense can be analyzed.

 

It would depend greatly on the extent of commonality between propulsion schemes used on the guideway and on the street.  For instance, the use of linear synchronous motors on the guideway would require an essentially different propulsion system for street and guideway.  Further, it would depend on the extent that redundant safety apparatus and controls are thought to be required on the vehicle. Initially, at least, this could be considerable. If it turns out that the ratio of vehicles to pallets is in the range of ten to twenty, it is not at all clear that that providing the additional apparatus to each street vehicle is an economic positive.

 

There is very little data upon which to make an estimate of the vehicle to pallet ratio.  One indication comes from Andreasson[5] in his Gothenburg simulation. We believe a fair reading of the data suggests a number greater than ten.[6]

 

This would not necessarily directly apply to a real dualmode system. There are a number of factors that differ between some proposed systems and the Gothenburg simulations. For instance, the simulation contemplated a system speed of 21.6 miles per hour (36 kilometers per hour). Many proposed dualmode systems posit speeds of 60 to over 100 hundred miles per hour. To first order, leaving everything else the same, the ratio would scale with system speed. Thus an average of 80 mph would suggest an increase in the ratio by approximately four. On the other hand, the average distance traveled in the Gothenburg study is 3.78 miles (6.3 kilometers); our opinion is that in the United States this would be significantly higher, thus tending to reduce the ratio.

 

Another factor that must be considered is the so-called "empty pallet" problem. Data for Los Angeles freeways[7] provides that the split, or D factor (i.e., the percentage going in the peak direction during the peak hour), is typically in the in the mid 50 percent range and only occasionally rising to the low sixties. If we err on the conservative and assume that demand is represented by a 60 percent split, then an ideal solution would require only an additional 20 percent of empties travelling in the non-peak direction; resulting in approximately 83 percent of the travelling pallets providing revenue. This, of course is an idealization of the situation, undoubtedly, real operation involving depots, waiting times and the like would reduce this quantity.

 

The data generated in the Gothenburg study represented typical demand matrix representative of a system wherein traffic is mostly in one direction. In a typical urban environment, the above discussion underscores that the traffic is decidedly not simply one-way. Thus one would reasonably suspect that the utilization of pallets in a dualmode system would be significantly higher than would be suggested by an extrapolation from the Gothenburg study.

 

 

E.     Palleted Systems are Heavier and More Complex

 

It is, unfortunately, true that palleted systems are likely to be heavier and more complex.  There are no perfect solutions, and additional weight and complexity may simply be the price for other advantages. 

 

The question of additional weight would be particularly burdensome if the system were considered as an elevated system.  As we stated at the outset, it is our thought that this would be the exception, rather than a general rule.  Of course, on- and off-ramps will still require isolation from other traffic.  Certainly if one anticipates right-of-way access along existing freeways, this no doubt mandates elevated structures.  It is difficult to argue that additional mass is a good thing (except, maybe, in a collision), but with the majority of the system at grade we believe it an acceptable tradeoff.  

 

Primary among issues of complexity is the requirement to provide an adequate supply of pallets for incoming vehicles.  Failure in this will seriously jeopardize our ability to meet the traffic-handling objectives.  The need to forecast traffic accurately is essential.  In this, are ability to develop adequate quotas goes hand-in-hand with the need to provide and adequate supply of carriers.  While all this is certainly true, it will require thinking the problem through, once solved (and with continuously updated input) it remains solved.

 

    A corollary of this is so-called “empties” problem.  As discussed above, this is probably not as serious as some portray it, i.e., the assertion that traffic is almost completely one way.  From our previous discussion, we know this not to be true.  Nevertheless, this whole issue does considerable complicate operation.  It will no doubt be necessary to provide off-line storage depots to provide strategic placement of empty carriers.

 

It is also true that somewhat more complex stations are required.  It will not be sufficient to just drive up to an on-ramp.  Nevertheless, we believe all of these are tractable.      

 

 

F.      Summary and Discussion

 

Given all this, and for the reasons detailed, we argue that all dualmode systems should be designed as palleted dualmode, certainly for the present.  As we stated at the outset, the arguments are not all one way; but, on balance, we believe them to favor palleted dualmode.

 

 We have no quarrel with those that would look ahead to the possibility of true dualmode, and thus may wish to design so as not to preclude this; we simply argue that no great weight should attach to it.  Any final design will most likely be substantially different from any that are envisioned today.

 

It has been suggested that in a true dualmode system, the extra cost of outfitting a street-legal vehicle to transit the guideway is not really part of the system cost (i.e. that these should be assumed by the vehicle owner).  Thus the only cost is the guideway.  Others have even suggested that a separate entity assume the cost and operational responsibility for the pallets. This is all patent nonsense. The system is the system; and the cost is the cost. We do not support any effort to obscure what it is.  It will be paid for by the taxpayer/user no matter in what form.  No creative financing is going to reduce it. It may make it more palatable to some (please pardon the pun); but it will not reduce it.  We believe the many advantages cited will be sufficient to overcome financial difficulties without resorting to subterfuge.

 

There are surely additional issues that bear on this question, but we believe the central points have been identified and, in our opinion, established.  That is, at least initially, dualmode systems must be palleted.  Moreover, we believe it remains a doubtful hypothesis that a true dualmode system is optimum.  Nonetheless, as we stated in the preface, ours is not a universally shared view.

 


[1] It has been suggested that the operating agency either provide or lease the vehicles   Others have suggested a massive tax advantage be given to owners such vehicles.  We consider this either impractical, or unfair.  It would be impractical to provide a street legal vehicle to any one who wishes it, and it would be unfair to those to those who can not use one to, in effect, pay an additional tax for a non-dualmode vehicle.  If leased at a fair-market value, that would be essentially the same as a purchase.

    

[2] John P. Hopkins, Volpe National Transportation System Center, Cambridge, MA

 

[3]  Hopkins, J. B. and Reynolds, F. D., “Considerations of the Need for an Integrated Dualmode National Transportation System”, http://faculty.washington.edu/jbs/itrans/hopkins.htm,7 May 2001

 

[4]  Harris, Richard, “Palleted Cars Can Help Us Move Forward”, http://faculty.washington.edu/jbs/itrans/authurdualmode.htm, 27 May 2002

 

[5] Andreasson, Ingmar, “Vehicle Distribution in Large Personal Transit Systems”, http://faculty.washington.edu/jbs/itrans/ingsim.htm, 21 April 2001

 

[6] If we consider Table 2 and take the ratio of 'passengers departed per cab hour' to 'loaded cabs departed per cab hour' (4.3 / 2.1 = 2.05) we get a number slightly greater than two. That is there is one cab for every two departing passengers. The difference of this quantity from the average of 1.76 is easily explained by the fact that all passengers do not exit at the same station. Nevertheless, If we apply this ratio (2.05) to the total estimated daily traffic i.e., 600,000 passengers, we obtain something over 293,000 cab departures per day. This undoubtedly underestimates the actual number as it would seem likely that the number of passengers carried per cab during off hours would be less than those for peak hours. Nevertheless, having no better number, we will continue its use. As there are 12,795 cabs, this would suggest that, on average, each cab makes 22.9 revenue departures per day. It is interesting to note that if we extend the peak value of 2.1 departures per hour, we obtain something over 50 revenue departures per day.

 

Palleted dualmode journeys are likely to be a round trip i.e., a minimum of 2 journeys a day for each vehicle. Thus to extend the above number to dualmode, the appropriate ratio of vehicles to pallets is more like half of the cab departures, or 11.5.

 

[7] 1998 Traffic Volumes on the California State Freeway Systems, State of California, Business, Transportation and Housing agency, Department of Transportation, June 1999