XI   SUMMARY AND DISCUSSION

 

          We assert, without total proof, that a guide-based system consisting of numerous intelligent, independently operating car-ferries is both a technically feasible and practical solution to urban trans­portation.  Without overwhelming proof, yes; but not without considerable rough logic - and certainly sufficient justification to warrant additional study.  

 

          We have postulated a theoretical maximum main line capacity approaching 17,000 vehicles per hour.  This goal will not be completely achievable throughout the system; no transit system operates at capacity everywhere.  However, we have provided calculations that suggest that something like 15,000 (14,750) VPH is possible. 

 

          Even at maximum loads, it will probably not be possible to exceed much more than 85 percent of the theoretical maximum.  Nevertheless, we suggest that a peak capacity of something like15,000 VPH makes a favorable com­parison to the 2,000 or so of a single freeway lane. 

 

          To put this in context, we submit that a capacity in the neighbor­hood of one-half of this would still be an attractive proposition.[1]  Please do not be mislead, we are not nearly that pessimistic.  While some might question, in some respects, some assumptions; we do not consider that they are in error by a factor of two.  For instance, our assumption of a system speed of approximate­ly 80 miles per hour; few would argue that a safe maximum is only forty miles per hour.  Further, consider a minimum safe headway of 150 feet; even if one insisted that this must be at least 300 feet, the system capacity is reduced by less than 30 percent.  And so forth.

 

          Let's be very clear about this.  Once the packet configuration and system speed are set, there can be little doubt that a single track can physically accommo­date the traffic.  While due consideration must be given to allocating priorities, maintaining equity of access, and providing the necessary flexibility to accommod­ate varying demands; it seems most likely that that something very much like the calculated peak capacity can be reached.  The limitation on total system capacity will, more than likely, be the aggregate station capacity. 

 

          Just how many stations, with what capacity, and how rapidly they are provided, is to a large measure a function of one's traffic objectives.  We most certainly do not argue that the whole system should be converted to rail in the first instance.  One might, initially or forever, view the rail-based system as a means to relieve freeway congestion and thus provide easy accommodation for relatively short journeys; while relying principally on the rail system for more lengthy ones.  By emphasiz­ing longer commutes, the required number of stations is reduced.  If desired, such a policy can be enforced at the entrance station. 

   

            Whatever the objective, it seems more than just merely likely that the requisite station capacity can be provided.  As we indicated, a capacity exceeding 2,000 vehicles per hour is achievable in a single departure station; and that as few as four docking positions could provide a capacity of 1200 vehicles per hour.  A similar capability can also accommodate incoming vehicles.  Different assumptions will provide different results.  As before however, we submit that our assumptions are not grossly invalid, and that in any event small changes can provide the requisite capacity.   

     

          Thus, with some confidence, we further assert that a system along these lines supports a number of important advantages.  Among these: efficient utilization of rights-of-way, and concomitant economic savings; compara­tively effortless and efficient commutes; favorable environmental impact; and reduction of the freeway accident toll.  At this point, it might be useful for the reader to review the details of Section III. 

 

          As was intended, the emphasis has been on the management and operation of a complex system.  Although specific new design will be required, we submit that no new breakthrough-technology is necessary.  We have identified collision avoidance as an area that should receive early attention, but even this does not qualify as breakthrough-technology. 

 

          This is not a totally new concept; aspects of this have been considered before.  Never­theless, it may just be that recent progress in computer and communication technology, coupled with burgeoning traffic congestion and increased environmen­tal awareness, all combine to suggest that this is an approach whose time has come.

 

          We are not unmindful that, if fully implemented, such a program would be a massive undertaking - something approaching the grandeur and scope of the modern freeway system.  But as with the first freeway, the initial implementation could have limited extent and limited objectives.  If the initial experience were to prove successful, like the freeway, the system would grow only as fast as was deemed practical, and funds were available.  And here we must emphasize; that we are not proposing to re­place freeways, but rather to augment them.

 

          Moreover, we are not now advocating anything remotely approaching immediate implementation.  On the contrary, we suggest only that further study seems warranted and that, in particular, a comprehensive computer model be generated to study various aspects of total system operation.

 

          Finally, it seems appropriate to repeat what we set forth in the preface.  It is not essential that you, the reader, agree with every detail presented here.  It is only important that you gain some appreciation of the many advantages provided by this general approach.  If you come away with a sense that consideration of these may lead to a practical and economic solution to the problems of urban transit, we will have succeeded.

 


     [1] For Instance, a capacity of 8,500 vehicles per hour would accommodate 63 per cent of the busiest peak one-way traffic location on the Los Angeles freeway system.  Moreover, this is an extreme case;  the busiest locations seldom get much over 10,000 vehicle per hour. Taking 85 per cent of the vehicles off the overwhelming majority of the freeway system can hardly be considered an abject failure.  This overstates the case and our objectives.  It does, however, serve to illustrate that considerably less that 17,000 vehicles per hour would still be extremely useful.