THE REVOLUTIONARY DUALMODE TRANSPORTATION SYSTEM
On the Guideways
TRAVELING ON THE GUIDEWAYS
If we need to take the kids to school or go shopping a couple miles away, we will stay on the ordinary streets and our dualmode cars will operate just as we are used to cars operating, except for their quiet pollution-free power plants. If we have to go more than a few miles we will probably switch modes and use the guideways to save time, money, and avoid frustration.
There will never be any speeding tickets issued on the guideways, because everyone will be traveling at the same high speed all of the time. On the guideways the ride will be smooth and quiet except for the rush of air outside and perhaps a slight electric hum. There will be no passing or being passed, and the speed will be constant regardless of how heavy the traffic may become.
Once on the guideways the “driver” can take a nap, read, or watch television, because no driving duties will be required again until the car leaves the guideway system. Workaholics can work at their computers while traveling, including e-mail and the Internet. And persons who now recklessly eat, shave, put on makeup, or talk on cell phones while driving, will still be able to do these things on the guideways, but without delaying traffic or endangering lives.
The clearance between cars may be only a foot or less, but fear not, as we will see in Chapter 8 the cars won’t bump; the system will keep them spaced perfectly. On the guideway the cars will be like boxes traveling on a high-speed conveyor belt, their relative positions and the clearance between them will never change.
Things can travel safely very close together at high speeds if they are all forced to travel at exactly the same speed. You and I are both riding on a planet that is spinning and traveling through space at thousands of miles per hour, yet we can safely shake hands or hug, because we are synchronized with each other at the same speed and on the same path.
Likewise, nothing can go wrong with a car on a maglev guideway to cause an accident. Nothing in the car is being used in the guideway mode except the permanent magnets underneath that guide it, support it, and keep it’s speed exact. “What if the magnets should suddenly fail?” That is about like asking, “What if the coffee I am drinking suddenly froze solid?” I am not going to worry about that, because it just can’t happen. It never has and never will.
On the guideways the street-mode motor is off and all of the normally moving parts in the car are stopped. The street-mode tires are not even touching the ground. Since nothing is running in the car, nothing is wearing out and nothing can go wrong.
If the power to the guideways should suddenly fail the cars will gently delevitate, the wheels will again provide support, and the cars will coast to a safe stop while continuing to hold the same spacing (to be explained in Chapter 9). Sleeping travelers will probably be awakened by the sound of the wheels starting to spin, but even if the “driver” doesn’t awaken immediately there would be no problem because the vehicle will still be “on autopilot.”
Should power fail on one section of the guideway, or if a section is shut down for maintenance, that section will be instantly and automatically isolated from the system, and its traffic will be routed to a detour (Chapter 14, under Local Guideway Shutdowns).
A system where the cars ride on top of the guideways (comparable to highways and railroads) is likely; but the reverse configuration, where the cars hang below elevated guideways, would have some interesting advantages as well as disadvantages. Although these two guideway systems would look quite different from each other, technically and functionally they would be very similar. In a suspension guideway system the cars would hang from arms connected to fittings running inside of overhead channels. The street-mode wheels would never contact anything, even in the event of a power failure, as long as the cars were in guideway mode.
In either this suspended configuration, or in a normal elevated-highway-like configuration, in some areas the ground below the guideways could be left natural. In farming or range country, crops could be grown or animals pastured below active guideways, much as crops are now grown below electric power lines and wind turbines. All overhead guideways would be built high enough that the cars would be above the heads of people, animals, or vehicles passing beneath. This would eliminate the cost of safety fences and save animal and human lives.
Suspension guideways or elevated guideways would reduce snow and debris problems. In areas of heavy snow the guideway supports would be made higher so the system would operate above deep snow without the need for snow plows or snow sheds.
Passengers could leave suspended vehicles that are to be stalled for some time, by stepping from the car doors to a walkway paralleling the guideway. But these people would be leaving their cars and their belongings up in the air, literally and figuratively. To solve that problem we might lower the cars and their occupants to the ground by an automatic winch system and let them drive off in street mode. (I agree with you; those possible solutions are not very appealing.)
In a suspended-car system the cars could have suspension arms with magnet or roller assemblies extending about a foot above the car tops. But if these appendages were rigidly mounted there, many people would object to their appearance while in street mode, they would cause additional wind resistance, and they might require higher home garage ceilings.
Overhead assemblies on the cars might be retracted into a fairing on the car roof or elsewhere, but a simple practical and attractive configuration is not obvious. Another approach would be to detach the cars from the overhead assemblies and leave the suspension assemblies hanging from the guideways to be routed around to where they are needed by other cars. These would be suspended pallets, with all of the disadvantages of regular pallets.
Perhaps the greatest objections to a suspended-car guideway system would come from the emotions of some potential users. A number of people who ride airplanes with little concern would object to riding in a car suspended above the ground. Such people likely refuse to ride funiculars, ski chair lifts, or to go up in hot air balloons. But most people soon accept useful new things once these are shown to be reasonably safe. However, all factors considered, my personal vote is against cars suspended below the guideways. Supporting the dualmode cars on top of the guideways seems to have many more advantages and fewer disadvantages.
WHEELS ON THE GUIDEWAYS
I strongly favor magnetic-levitation (maglev) cars and guideways (to be discussed in the next chapter), but alternatively we could support the dualmode cars and other vehicles in guideway mode on wheels of some kind. There are two main wheel-type choices: The simplest and cheapest would be to use the same wheels and pneumatic tires on both the streets and the guideways. But “simplest and cheapest” isn’t necessarily wisest. One US Astronaut in space is reported to have said to his partners, “Doesn’t it give you a good feeling to know that this space vehicle was built by the lowest bidder?” Can we build pneumatic tires that would be adequately safe and last long enough for automatic high-speed guideway use? I am skeptical.
The other wheels choice would be to use pneumatic-tired wheels in the street mode and provide a separate set of wheels on each vehicle to ride rail-type guideways. A number of ways of doing this have been proposed. One way would be to put the four rail wheels on the same axles as the four street wheels, a bit like dual tires on trucks. But the rail wheels would be smaller than the street-wheel tires so that the rail wheels wouldn’t touch the ground in street mode. On the guideways the larger pneumatic tires would freely extend down below the tops of moderately high rails.
We wouldn’t use the noisy rapid-wearing derailment-prone flanged wheels the railroads use, however. If rail-type dualmode guideways were used they would need a different guidance and switching system (Chapter 12) that would allow the use of quieter, smoother riding, and much safer flangeless rail wheels. But compared to maglev, using any type of wheels on the guideways would stink. Don’t use them—please.
BUILD MODERATE-SIZE GUIDEWAYS
Naturally we should not waste money, but the old “Penny-wise but pound-foolish” saying holds much wisdom applicable to a dualmode system. The cost of the national automatic guideway network is going to be enormous, and that fact will tempt many of the planners to try to save a few billion by degrading the performance, capacity, convenience, speed, and/or safety of the system. We must be very cautious in evaluating such cost-cutting proposals.
For instance we could build cheaper guideways if they were lighter and accepted only small vehicles. But it is unlikely that we would be able to get a high enough percentage of the population to buy only small light dualmode cars. Therefore small guideways would be less used, highways would still be crowded, the remaining fossil fuel would still be going up in smoke, and global warming would still be escalating. Also the small light guideways couldn’t accept moderate freight vehicles or medium-size transit buses. The total income from a small cheapie guideways would likely be so low that the system would require subsidies or go bankrupt. Wrong way to go. The prime objective of The National Dualmode Transportation System should be to satisfy the majority of the travelers and accommodate most of the express cargo.
Or we might “save billions of dollars” by building a lower-speed national guideway system. But a slower system would have less capacity in vehicles per hour. And if it wouldn’t have speed advantages over the cars, buses and trucks on the highways, the railroads, or short airline flights. People won’t pay guideway use fees unless there are significant advantages for them to do so. If the system couldn’t attract a high percentage of its potential customers it wouldn’t solve the problems it was designed to solve, and it would lose money. Likewise, the lower capacity of a slow system would require more guideway lanes, and “saving money” by reducing speed could actually end up costing more.
Unwise attempts to save in the system design and construction could cause the transportation revolution to fail, with nothing to show for the great upheaval, cost, and time loss. Worse, people would have “learned their lesson,” and it would be next to impossible to get their support to rebuild the system. We have to do it right the first time.
TYPES OF VEHICLES
Most of the guideway traffic will consist of passenger cars of various types and sizes, just as highway traffic now does. Dualmode cars may be as different from each other as our present automobiles are. And these cars may look a lot like what we now have, be painted our favorite colors, and be made by our favorite companies.
Very small cars have had limited popularity in affluent countries, partly because they are less safe in highway traffic than larger heavier cars. But on the guideways small (even single- or two-passenger) cars will be as safe as large cars, will cost less to buy and operate on both the streets and guideways, and will have a number of environmental advantages. It is hoped that practical small cars become more popular in our dualmode-transportation future. Delivery trucks and school buses will of course be dualmode. There will be two or three different dualmode transit services, and a unique driverless freight system, all to be described in the next chapter.
Even if internal-combustion engines are used in most of our dualmode vehicles initially, the rate of fossil fuel depletion will be greatly reduced and there will be less pollution, since these automobiles will be traveling on the guideways with their engines shut off a high percentage of the time. Later, when the guideway system is complete, most of the vehicles will be environmentally clean in both modes.
THE GUIDEWAYS MUST BE EXTENSIVE (and will be expensive)
If the national government should fail to initiate a dualmode system it would be difficult for individual states, counties, or cities to build independent dualmode systems because the small populations served by them couldn’t afford the design and development costs. Guideways restricted to a local area wouldn’t carry many dualmode cars because not many people could afford special cars built without the major cost advantages of mass production; and people in such areas would need cars that could travel the highways in other areas. Therefore an isolated dualmode system would end up carrying palleted vehicles almost exclusively.
We must have a Universal Dualmode Guideway System. It will extend not only from the Atlantic to the Pacific, and from Maine to Florida, but eventually into Canada, Alaska, and Mexico. In fact, when South America develops further the Pan-American Guideways will cross the Panama Canal on the Bridge of the Americas so that we can ride in our own cars at high speed from Alaska to Buenos Aires.
The European dualmode system will of course use the Channel Tunnel to connect the guideways from Scotland to Italy. With Gibraltar-to-Tangier Morocco and Germany-to-Sweden undersea tunnels the guideways could be linked from Hammerfest Norway to Capetown South Africa. How about London to Beijing, and on under the Sea of Japan to Tokyo? Am I serious? Moderately so, but don’t expect all of this in the near future.
It is essential that the eventual INTERNATIONAL DUALMODE TRANSPORTATION SYSTEM be standardized so that any dualmode car from any country can travel the guideways anyplace else in the world, just as our automobiles can now travel in any country. Weights and measures have been standardized worldwide (if the US ever really goes metric), and television, the Internet, and phone systems are standardized. We must also have international transportation standards in this shrinking world.
Most of the people in the forefront of dualmode system development agree that the guideways must be high-speed in order to meet demands for increasingly rapid transportation, and to provide high system capacity with a single guideway lane in each direction. This single-lane system will minimize infrastructure costs, minimize the changes to existing infrastructure, and minimize additional rights-of-way required for the guideway system.
We could build a very high-speed system using maglev guideways (Chapter 9); but the higher the speed, the greater the radii required for turns, the longer the guideway entry acceleration and exit deceleration ramps need to be, the greater the noise, and the greater the energy and power needed. The power for higher speeds is of particular concern because the power required to overcome wind resistance (aerodynamic drag) increases as the cube of the velocity. This means that to go twice as fast we require eight times as much power. And 200mph guideways would require (200/60)3 or 37 times as much power as the 60mph guideways. But at the higher speed we would be using that power for a much shorter time, so we won’t need 37 times as much energy. The energy required for the 200 mph trip will be (200/60)2 or 11.1 times as much as for the 60mph trip. That is still an enormous penalty to pay for higher speed, and it doesn’t seem fair, but that is the way it is. Those who advocate lower highway speed limits to reduce the rate of fossil-fuel depletion have a strong argument. And unless we somehow develop an essentially unlimited sustainable source of cheap energy, speed selection will be a major consideration in the design of The National Dualmode Transportation System.
There is a way of greatly reducing the aerodynamic drag and the power required at high speeds, however. Airliners usually fly at very high altitudes because the air is a lot thinner up there, and that markedly reduces the drag. We could gain that great advantage on our dualmode guideways also, by putting them in tunnel-like tubes and pumping most of the air out of the tubes. The more we approach a complete vacuum in the tubes the lower the energy and power required to propel the cars, but the greater the power required to keep the tubes evacuated. Evacuated tubes would be more costly than open guideways for a number of reasons. For instance we would have to pressurize the cars, just as we pressurize jet airplanes. But at some point in the future evacuated tube guideways will be a practicable solution for long trips. Daryl Oster, and his Evacuated-Tube Technology Inc. is a current leader in evacuated-tube transportation.
The disadvantages of high speed are greater in cities and suburbs, and its advantages are greater between cities—so the author proposes two different fixed guideway speeds. Many factors will be weighed in making the final decisions but this book will assume that the guideways in and around cities will run at 60-mph (100 km/h, and the intercity guideways will run at 200-mph (325-km/h).
A word to calm the fears of some may be in order here. Two hundred miles per hour in our present human-driven automobiles traveling very close together would be out of the question, but the guideways will be quite a different matter. The automatic synchronization of the cars will make it impossible for them to crash into each other. Progress requires revisions in people’s thinking: In the horse-and-buggy era how many would have thought that we would be traveling safely at sixty miles an hour before long?
Neither my wife nor I experienced any feelings of concern when we rode a commuter “Bullet Train” in Japan at 120 miles per hour. In 2000 Erik Driessens, a Netherlands dualmode colleague and friend, rode a “Transrapid” maglev train in northern Germany. He wrote, “The ride was for 15 or 20 minutes and covered over 80 km. Their top speed was 403 km/h (250-mph) and the ride was very smooth and silent.” Erik loved it and felt completely at ease. Why not? We routinely travel twice that fast in jets.
THE REVOLUTIONARY DUALMODE TRANSPORTATION SYSTEM, “REV”
Across the United States there may be one northern and one southern 200-mph east-west guideway, and a large number of north-south and diagonal guideways between cities. All of these guideways will be connected into a readily accessible network largely paralleling our highways. The local 60-mph guideway grids throughout the country will connect with the 200-mph guideway network at frequent points. When the system is fully implemented there will be guideways at one speed or the other paralleling most highways and many streets throughout the nation. We will drive in street mode to and from our homes and on very short trips, travel on the 60-mph guideways for the major part of commutes, and be routed to the 200-mph guideways for longer trips.
The local 60-mph guideways will be the most useful for solving our urban traffic problems, so it is likely that many 60-mph networks will be built and used in and around the major cities for several years before the interconnecting 200-mph guideways are finished. The guideway networks of both speeds will expand gradually over the years, just as our street and highway systems have expanded.
On long stretches the guideways will be two-way, like our highways are, in order to conserve real estate. Conversely, one-way guideway grids in cities will greatly reduce the miles of guideway and the land needed, with only a very slight increase in average travel time. One-way guideway grids will be much less frustrating than unfamiliar one-way streets are, because computers will be doing all of the navigating.
All guideways must be effectively endless. One can picture the cars piling up in a huge continuing 60 or 200-mph crash if a guideway came to an abrupt end. A two-way-traffic guideway that does terminate must have a turnaround loop at the “end of the line” so cars approaching it will be looped back if they don’t exit the guideway there. (See Chapter 14).
Since the guideways will be able to carry an enormous amount of traffic (Chapter 9), one guideway lane should be plenty for many years; but eventually on the most dense traffic routes a second guideway lane will be needed.
When it approaches a large city the 200-mph traffic will fan out from a single guideway into a number of 60-mph guideways, much as manually driven cars fan out and merge in our highway system. Inter-guideway acceleration ramps will take the cars from sixty to two hundred miles per hour, and deceleration ramps will be used to reenter local 60-mph guideways.
Like train tracks and highways, the guideways will be at ground level, elevated, in tunnels, and on bridges. Overpasses or underpasses will be required at all guideway interchanges, and at crossings with streets, highways, and train tracks. In existing dense urban areas we will usually have to elevate the guideways or put them underground, just as we do trains and subways through cities.
Slightly elevated guideways will probably be built in highway median strips, thereby reducing the need for acquiring more land. In addition to paralleling highways, some guideways will probably be built along abandoned or active rail rights-of-way, and others may be built in power-line and pipeline rights-of-way.
Park-and-ride lots will disappear when we have dualmode, but additional parking space will be needed at final destinations. Factories, malls, and sports stadiums require lots of parking. In these areas, and at homes and in suburban areas where the cost of land is moderate, the cars will leave the guideways and be parked manually by their drivers. But in urban areas many businesses, sporting facilities, and other organizations will provide multi-story automatic parking directly from the guideways. This system, which will greatly reduce both urban street traffic and street parking, is explained in Chapter 13.
STRINGS OF CARS ON THE GUIDEWAYS
The guideway-system computers will attempt to establish strings (lines or queues) by merging entering cars adjacent to cars already on the guideways. Compactly stringing the cars will maximize the useable capacity of the guideways. And forming long continuous queues of cars will save a lot of power by greatly reducing the wind resistance per car. In layman’s terms, the leading car has to push open a path in the air, which the following cars can more easily slide through. The NAHSC estimated thirty-percent reduction in drag with cars traveling 13 feet apart. With cars only one foot apart, the drag reduction could well be fifty-percent or more. The system computer will attempt to position entering cars either at the end of a “solid” string of cars or at the front of a solid string. This will maintain the low drag advantage of close headways, as well as largely eliminate capacity-robbing gaps too short for a car.
On the highways increasing the space between cars increases the safety. The saying, “Don’t follow too closely” is good advice for fallible human drivers. But on the guideways the reverse will be true. The closer together two objects are traveling at the same speed, the less threat they are to each other. Guideway cars running close together will be unable to bump each other hard if the speed of one of them should start to change, because there won’t be enough room between them to permit the development of a significant velocity differential or “bumping speed.”
But actually, as we will see in Chapter 9, the speed of one of them couldn’t change. Railroad cars that are coupled together are “synchronized” by the couplings, and can’t crash into each other. The guideway cars will be synchronized by magnetic couplings instead of steel couplings, but the forces will be just as real and ample.
Trains are noisy at any speed because in addition to their very noisy locomotives they use screeching flanged-steel wheels on steel rails with imperfect “Click, Click, Click” joints. Automobiles are noisy because of their internal combustion engines and their tire treads. Airplanes are noisy because of their jet engines, or IC engines and propellers. Running on maglev guideways the dualmode cars will be quieter than trains, automobiles, or airplanes, because their street-mode motors will be shut off and no wheels or tires will be touching the guideway.
But any type of vehicle will generate considerable rushing-wind noise if it travels fast enough. At 200 miles per hour between cities a maglev car on the guideways will make more noise than it will when traveling on the 60mph city guideways. However, overall the dualmode system will significantly reduce average noise levels throughout the nation since it will reduce automobile, train, and airplane traffic. People living close to railroads, airports, and on airline flight-paths will be especially grateful for the guideways.
In some places the two-hundred-mph guideways will not parallel the highways since some of the curves on existing highways are too sharp for 200-mph speeds. Curves on railroads are gentle, so some of our high-speed guideways are expected to find homes in railroad rights-of-way.
In curves the guideways will be tilted (“banked” as airplane pilots say, or “super-elevated” as highway and railway engineers say). The bank angle will be just the right amount so that no side forces will be imposed upon the vehicles or the passengers. On the 60-mph guideways the radius of the turns will be comparable to those of turns on our highways. On the 200-mph guideways the radius of the turns must be much larger in order to preserve passenger comfort. Unfortunately centrifugal force varies as velocity squared, so adding a little more speed requires a lot more turning radius. Jet airliners must also make large gently banked turns for passenger comfort, but they have the freedom of three-dimensional space in which to set their personal courses.
If my arithmetic is correct, the radius of a turn on a 200mph guideway needs to be 4,628 ft. if the bank angle is limited to 30° (the angle airline pilots try not to exceed in order to avoid frightening their more timid passengers). The G-factor in this case is 1.15: A 100-lb passenger would feel like she weighed 115 pounds in the turn. This G-force is obviously very low, but that is how it comes out when we restrict the bank angle to 30° and push the passengers straight into their seats, not toward the side of the car. The bank angle has proven to be the factor that concerns timid passengers much more than the G-force does. Roller-coaster fans love the feel of tipping, including clear over, as long as they are firmly pushed down into their seats. Could everyone learn to peacefully accept more than 30° in turns? This would allow sharper turns and would reduce the amount and cost of real estate for the 200mph guideways.
(You were warned that this would be a semi-technical book; but if these last few paragraphs have not been your literature of choice, don’t read them.)
Maglev cars could be designed to climb as steeply as automobiles and trucks can; but the maximum guideway grades will probably be comparable to maximum highway grades since the guideways will usually parallel the highways. Maximum railroad grades are less, since steel wheels on steel rails don’t provide enough traction for steep grades. The linear motors in the guideways would have to be more expensive and consume more power if they had to climb excessive grades, so let’s keep the maximum grades moderate.
On the Synchronous guideways the cars won’t slow down when climbing hills; the traffic will always run at full speed at all points in the system except in the entry and exit ramps. (Chapters 9 and 11)
When going down hills the linear synchronous motors will operate as AC generators (alternators) providing “regenerative braking” and keeping the cars from speeding up. Automobile brakes waste energy, turning it into heat; but the regenerative braking will save a lot of normally-wasted energy by converting it back into guideway electricity. Descending cars will thus indirectly help other cars, and increase the efficiency of the system.
Hybrid automobiles, with a small gasoline engine a large battery and an electric motor-generator, save energy in several ways, an important one of which is by pumping energy back into the battery when they are going downhill. Hybrid diesel-electric locomotives for railroads are also gaining in popularity. Instead of wasting energy in friction brakes or electric resistors when the trains are decelerating or going downhill, the electric motor-generators of hybrid locomotives help to recharge electric batteries and thereby improve their overall efficiency. The National Dualmode Transportation System, using linear synchronous motors, will do the same thing: save and reuse much of the potential energy being expended when going down hills, instead of wasting it by converting it to heat. This is only one of a number of ways in which our coming dualmode system will conserve energy.
THE GUIDEWAY COMPUTER SYSTEM
Computers will completely control all aspects of guideway travel; but unlike our personal computers we will not see the guideway computers and will be little aware of their actions. Things will just happen automatically, as they do in so many other marvels in our modern world. There will be one top computer in the system (It won’t be “Hal”). Reporting to this electronic CEO there will be supervisory and worker computers. These will have specific duties such as electronically processing cars wishing to enter the guideways, accelerating them to guideway speed and merging them with the traffic, navigating them to where they want to go, delivering them back to the streets at the end of their guideway journeys, and automatically billing the travelers for their use of the guideways. (Someone has to pay for all of those computers.)
Our highway system has many “computers” too, the brains of us drivers. But when we are driving little communication is possible with nearby drivers, or with the rest of the highway system. On the guideways constant communication between the computers will result in a much more efficient, faster and safer system.
If you are worrying about possible computer failures, remember that human-brain “computer” mistakes and stupidity are the chief cause of accidents; but computers are much better than human brains in many ways, that is why we use them. There are also a number of computers in the modern automobiles we drive. We trust many more computers in the jets we ride and in the air-traffic-control system. The passenger-mile accident rate for airliners is very small compared to the driver-caused-accident rates for automobiles.
Wherever the function of a computer is vital to safety there are always backup computers and other safety provisions. Such systems are designed to be “failsafe.” That is, they are configured such that the system can only fail in a safe mode. There will be a simple computer or two in each guideway vehicle, but tampering or failures in these will be unable to cause accidents. All of the vital guideway computer system will be in locked underground vaults. Viruses will not be a problem since the guideway computer system will be completely separate from the Internet and inaccessible to the hackers and terrorists.
The local control centers, perhaps one for each major section of guideway, might be compared to airport control towers; but the guideway computers, not people, will be in control of the guideways. Pilots, human air-traffic controllers, and railway-traffic controllers are fallible, as we often read. Fortunately we won’t need, and will wisely exclude, human control of the guideway traffic.
“If computers are so great why don’t we get rid of the human air-traffic controllers in the airport towers and have only computers there?” Because our airplanes still have human pilots who make observations and decisions that need to be verbally communicated to the human controllers. And the human controllers read the radars, the weather reports, and the traffic data and computer data, so the humans are needed to give verbal information and directions to the pilots. The air-traffic control system started long before we had computers, and it is still a human-oriented system. Human pilots can fly in any direction, including into mountains, storms, the ground, and into each other. All of the above still occur sometimes. And sometimes an air-traffic controller is at fault.
But we will be starting fresh with the dualmode system, and we can design it for optimum use of the latest automatic computerized sensor and control technologies. The guideway computers will be able to do the total job much safer, faster, and for less money than humans ever could.
Next: CHAPTER 8
Transit and Other Vehicles
Back to: CONTENTS
Last modified: August 01, 2006