I covered this subject in the book. Here are some updated thoughts about various systems.
*Telecommuting* Still the best answer for most work-related transportation needs. I predict this will be the best solution forever. At least on one planet. Obviously would not work well between the Earth and Mars. It would be difficult from the Earth to the Moon because of the time delay. I recommend small satellite offices rather than working from home. *Automobiles* Progress in self driving automobiles is occurring much faster than I imagined it would. I think it is essential to have self driving automobiles as soon as possible. This will greatly reduce the number of accidents and it will improve the flow of traffic. People do not realize the potential for the latter. The thing is, fully computerized cars will cooperate with one another better than human drivers ever could. They will "know" the intentions of all other cars. Thus, for example, you could eliminate many traffic lights and replace them with stop signs. A car approaching an intersection would receive a signal from an oncoming car warning at that the oncoming car intends to turn in front. Or he would receive a signal saying that the car intends to stop and wait for another car to cross. Where there are still traffic signals, all of the vehicles could communicate with a traffic signal to arrange optimum wait times. I predict that the bulk of transportation will be met with automobiles far into the future. That is, individual, ground-based wheeled-vehicles that transport people or freight from door to door. Some of the may be much smaller than today's automobiles. For example vehicles that deliver groceries or mail may be the size of a shopping cart. I predict that taxies will become much more popular than they are today in many places including suburbs. They will resemble today's Zip cars more than what you think of as a taxi now. That is, you will call one on your cell phone or computer and it will show up at the door when you need it. The problems with today's taxies are: They have human drivers so they are expensive. The drivers are often surly or they drive like kamikaze pilots. Robot vehicles will eliminate this. Taxies are often late coming. This is partly because traffic is so unpredictable today. Future traffic control systems, underground roads, and robot drivers will reduce this problem. Taxies are often dirty, or poorly maintained. In the future they will be cleaned up after every passenger by a robot, and thoroughly cleaned at the end of each day. They will be kept in perfect operating condition by robot labor. I expect that many other machines, houses, and infrastructure will also be kept in better condition than today. The advantages of using taxies in the future will be: This reduces the parking problem. The taxi takes you to your destination and then drives a way to pick up some other person. It is not left downtown all day long taking up space. This problem can also be reduced by having self driving cars drop you off at your destination and then drive a considerable distance to an underground parking lot, or even back to your house until you are ready to go home. It reduces cost of ownership. It spreads the cost among many people. The cost of ownership of automobiles will also be greatly reduced because automobile accident insurance will not be needed. Robot vehicle accidents will be extremely rare. Probably about as rare as today's commercial aircraft accidents. When robot vehicles have accidents it will probably be front page news. The cost of such accidents will be covered by society as a whole. They will be so rare it will not be worth bothering with individual insurance policies. This is how air travel works today. Every ticket comes with built-in insurance, which probably costs a few cents. This also reduces the hassles of owning a vehicle. Many of these hassles will be reduced anyway, because the vehicle will largely maintain itself. When it is time for routine maintenance, the vehicle will drive itself to the dealership in the middle of the night. Robots will test it, change the lubrication, rotate the tires and so on. The car will be back at your house before morning. By the way, I do not expect tires will be pneumatic. If they are they will have permanent pockets of air like a sponge. *Air cars and VTOL aircraft* I stick to the predictions I made in my book. Small VTOL air cars I do not think these will be as popular as some people predict, because they will be disruptive. I do not want to see cities and towns with many vehicles cluttering up the airspace everywhere you look. I predict the things will only be used at a few places around cities. Perhaps where we now have shopping malls. A stream of vehicles go up and down in five or 10 locations in a major city would not be so bad. Having vehicles take off and land in any neighborhood anywhere in the city would be disruptive. VTOL aircraft may be quiet in the future but they will not be silent and they will certainly produce a great deal of wind. These damned leaf blowing machines are bad enough. Direct VTOL shipments to large factories and production plants might be a good idea. These should be made mainly at night. *Underground roads* I think this is the ultimate solution to most transportation in cities and within 100 km of major cities, and also high-traffic used highways between cities. I think these will be shallow tunnels with many access points. Where tunnels cross underground, they will have small cloverleaf exchanges, similar to today's highways, except the speed will be much lower; at a walking pace. Cars entering and exiting highways will inform other cars so there are no collisions no difficulty changing lanes. The SwissMetro plan called for maglev trains running in partially evacuated underground tunnels. This was intended to reduce energy consumption. That will not be necessary with cold fusion. Perhaps lower air pressure would also increase speed and reduced noise. I do not know, but I doubt it will be necessary or desirable. If you want high speed I think you should stick to aircraft. I do not think that maglev trains will be popular either underground or aboveground. They are too inflexible. I think individual vehicles will use the tunnels. They will run at moderate speed roughly 3 times faster than today's automobiles (around 180 mph, or 290 km/h). NASCAR racing cars can achieve this speed. The limiting factor is safety. What is the fastest speed at which a car can have an accident and still have the passengers survive? The answer is roughly 290 km/h because that is the speed of NASCAR wrecks, and in most cases the drivers survive. Vehicle wrecks will not cause fuel explosions which are a major source of injuries and death. *Space elevator* The distance to geosynchronous orbit is 36,000 km. The first versions of this now being planned will use thin flexible material; fabric. Or ribbon, as they call it. The only way for a vehicle to climb this is with a pinch roller. I suppose maximum speed would be around ~100 km/h. That would take 15 days. That is too slow for tourists. A space elevator made of rigid materials, like a tower, could use a vertical maglev train. I suppose this could reach 1000 km/h, making the trip in 36 hours which would be more like it. For the first-generation elevator, I wonder if it would be possible to use a gigantic conveyor belt, with fabric 72,000 km long. In other words, a gigantic loop. With that arrangement, you could leave all of the mechanical equipment on the ground. The fabric would have hooks sewn into it every thousand kilometers. You would hope the car to the fabric, and then pull down on the other end of the loop with pinch rollers on the ground. This would pull the car up. After the first car has gone up a few thousand kilometers you would add another car. The present plans call for fabric that is thicker and wider in places where there is space junk orbiting, so that a small piece of debris will open a hole in the fabric without cutting it. They also plan to move the base of the ribbon back-and-forth so that orbiting junk misses it. I think this is a bad solution to the problem. I think it would be better to send specially built cars up the ribbon and use them to intercept the orbiting debris, thereby gradually getting rid of it. Perhaps you could use interceptor shields set at a 45° angle so that debris whacks into it, fragments, and the fragments fall to earth. - Jed
