Chapter 4
Dualmode vs. Single-Mode Transportation


Automobiles, trucks, trains, buses, and streetcars are all “single-mode” systems.  That is, these vehicles operate on streets and highways or on rails; none of them travel on both roads and rails. 


Most trips these days are made door to door in a single vehicle.  That is the most convenient and time-efficient way to travel, and that is the way most of us will still travel in the future.  But a few of us now drive a private car to a park-and-ride lot, and then ride a transit bus.  And on longer trips we may use park and ride, transit to the airport (or train depot), then jet to another city, then take a shuttle bus, and then a rental car or taxi to our final destination.  We may use five or more different single-mode vehicles in a single long trip.  The associated walking, waiting, and the transferring of people and luggage from vehicle to vehicle, often in the rain and in unsafe places, is obviously costly in terms of dollars, time, stress, and danger.  But in the future only one vehicle will be required for any trip if that one vehicle is dualmode. 


“Multi-modal transport” is not the same thing.  It means the use of several different vehicles in different modes in one long trip, such as we have just described.  Dualmode transportation, all in the same vehicle, will not require changing from one vehicle to another.  These multi-modal vs. dualmode comparisons apply to carrying freight as well as people.


Major efforts are now being made to get more people to leave their cars at home in order to reduce street and highway traffic congestion, to save fuel, and to reduce air pollution and the rate of global warming.  This approach, as we have repeatedly seen, works very poorly because most people want to drive.  And transit that uses the streets and highways cannot provide significantly faster transportation until a high percentage of traffic is removed from those streets and highways.  And transit can’t pick up and deliver very many of its passengers close to their doors.  Yes, walking is good exercise, but we much prefer to choose where, when, and how far we walk, and in what weather; and we prefer not to have to carry loads such as luggage, kids, or groceries, or ride in wheelchairs under unfavorable conditions. 


(The following paragraph was in plain clothes until a fellow dualmode-system proponent previewed it.  He said, “That ought to be underlined, because it is the guts of dualmode.”  You are right, Dave, this is the crux of the whole concept.)  A dualmode system will get a high percentage of cars off the streets and highways, not by discouraging car use but by providing a very fast high-capacity alternate path for the cars to travel on.  This new path will not only let people use their cars; it will get them to where they want to go faster and safer.  It will greatly reduce pollution, and will not use fossil fuel.  And the guideways, in conjunction with the existing streets and highways, will still provide the door-to-door service that we now enjoy—or would enjoy if the traffic weren't so heavy. 



A “true dualmode car” is defined as a vehicle equipped to be driven on the streets and highways as well as equipped to run directly on the guideways.  Existing automobiles won't be able to ride directly on the guideways, but an ordinary automobile on a “pallet” will be able to travel on the guideways.  Different pallets for the dualmode system will be designed to meet all of the requirements of guideway travel as well as carry a car, boat, or some other cargo.  A comparable case would be a trailer carrying something on the highways that cannot run on the highways directly, such as a boat.  The details of the pallets will depend upon the details of the guideway system and upon the details of the cars or other cargo the pallets will carry on the guideways.  Pallets will be used in the early years of the dualmode system to carry conventional cars, because at first only a few guideways will be available.  In that early period the highways will still be used extensively, and few people will yet have dualmode cars. 


In the early form of dualmode mentioned in the previous chapter, the automobiles and their drivers and passengers are loaded and carried on trains.  In this case the “pallets” are big and carry many vehicles at once: They are whole railroad freight cars.  Another dualmode system of this kind is the one for carrying automobiles on trains in the English-Channel Tunnel.  It can carry 800 cars per minute on a single lane of track.  Palleted dualmode systems have also been proposed where the “guideways” would be dedicated freeway lanes, and the “pallets” would be special trucks designed to carry a number of automobiles and their passengers.  One proposal for such a system goes by the name of “CarBus.” 


Ferries for carrying cars over water are another form of dualmode system, one where the pallets are boats and the guideways are provided by nature and extend in all directions.  Yet another example of dualmode is the airplane, which uses a taxi, takeoff, and landing mode in addition to a flight mode.  Amphibians are triple-mode vehicles.  But our subject here is land transportation.


Compared to true dualmode, or to single-vehicle pallets, all multi-vehicle pallet systems suffer from degraded independence and safety for the passengers, and from time delays due to loading and unloading the multi-car pallets.  So palleted dualmode systems using highways or railroads are temporary expedients with limited advantages.  Therefore let us return to the discussion of the high-tech 21st-century National Dualmode Transportation System. 


As the guideway system expands, more and more people will purchase true-dualmode cars and fewer pallets will be needed.  But some pallets will continue to be employed for older automobiles and for such things as hauling boats and other trailer loads.  The rental of pallets, from companies like auto-rental agencies, is proposed rather than having pallets as an integral part of the guideway system. 


The use of true-dualmode cars will reduce pollution, be more energy efficient, and more convenient than using pallets.  A pallets-only dualmode guideway system without true-dualmode cars would have much lower net guideway capacity because when the automobiles left the guideways and their pallets the vacated pallets would have to be routed empty on the guideways to locations where entering cars need pallets.  Unlike a “deadheading” empty transit bus, which still needs a driver, a deadheading empty pallet will be routed automatically, but deadheading it will still consume energy and will cost as much guideway capacity as an occupied pallet or dualmode car will.  This won’t be a problem in the transition period, however: The routing of empty pallets while the number of true dualmode cars is still limited will not stress the capacity of the guideways, because the system use factor will be low during that initial period. 



The only kind of national dualmode system that can provide very high-capacity and low-travel-times with a minimum number of guideway lanes is one that will keep the guideway traffic running at full speed all of the time.  There cannot be any stopping on the guideways except in an emergency.  Dense guideway traffic will travel at the same constant high speed as light traffic, never slowing down as highways do. 


And the cars must also be able to travel close together in order to provide the needed high system capacity.  In the firm conviction of the author the best way to accomplish all of this is through the use of linear synchronous motors combined with maglev built into the guideways (explained in Chapter 9).  Since the guideways will be constant speed, all of the acceleration and deceleration of entering and exiting cars will be done on entry and exit ramps (see Chapter 11).  This is the way our highways work, but is quite different from, and much faster than, the way railroads work.  The guideways will probably look somewhat more like railroad tracks than like highways, but the similarity will be visual only.  In function the guideway system will be comparable to the way our highway system would run if the human drivers could and would drive optimally. 


Like train tracks and freeways, most of the guideways will be at roughly ground level, and on bridges and in tunnels.  Overpasses or underpasses are required at all guideway interchanges, turnarounds, and at crossings with streets, highways, train tracks, and other guideways.  In dense urban areas we will probably put our guideways underground or elevate them.  Subways and the “elevateds” have been used in some major cities for over a century. Elevated guideways will also make sense in many open stretches where they could be placed above the median between opposite traveling freeway lanes, thereby eliminating the need for acquiring more land.  Some guideways will probably be built along abandoned or active rail rights-of-way.  Guideways through agricultural fields could be elevated so that crops could be grown beneath them, just as power lines are. 



          The cars to ride pallets on the first guideways will be conventional automobiles.  The true dualmode cars a little later could also look like current automobiles externally, but there will be major advantages to shaping them more like blunt-ended railway cars, so as to minimize the air resistance or “drag” when running them very close together on the guideways.  (See Chapter 7, under STRINGS OF CARS ON THE GUIDEWAYS.)  In the past fifty years most cars have been more or less “streamlined” in order to improve their mileage at high speeds on the highways.  But on the guideways, with closely spaced strings of cars, the opposite will be true: Cars that have blunt ends that match the blunt ends of the cars in front of them and behind them will be the most efficient, and therefore require the least energy and make possible the lowest guideway use fees.  You wouldn’t like the looks of blunt ended cars?  Going back a century, most cars had blunt ends, because they didn’t travel fast enough that the resultant higher aerodynamic drag made much difference.


What happened when streamlined cars started coming out?  Initially they were unpopular because they didn’t look like the cars we knew, but we got used to them.  Now blunt ended cars are common again (vans, SUVs, Jeeps, and Hummers).

          When dualmode cars are parked or driving on the streets little if any of the features that allow them to run on the guideways will show since they will be retracted.  Inside of the dualmode cars we will see much of the usual array of pedals, steering wheel, levers, and knobs, because these will all still be needed for driving in the street mode.  But the instrument panel will be moderately different.  Without a gasoline engine we will no longer need a gas gage, oil pressure warning light, etc.  But we will have some new instruments to keep track of such things as the charge level in the battery that will provide power in the street mode. 


And we will have a computer monitor and keyboard as well as a microphone and speaker to keep in touch with the guideway system.  Oh, and we will have a built-in telephone, personal computer, and a TV set, because we will have lots of time for work and pleasure while we are on the guideways and have no driving chores. 



Dualmode History


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Last modified: August 01, 2006