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Tracked PRT System
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(+3, -2)
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I found a few similar ideas on halfbakery (in fact, it's how I found the site), but I they weren't quite the same. If this seems like a repeat at first, please bear with me and thanks for your patience.

Basic Concept
Erect a series of “conveyor belt” tracks above existing roadways. The tracks would run about 20 feet above the roadways, in sections about 20 to 30 feet long. Each section of track would have its own motor and radio receptors and move independently of the others. Multiple lanes, turnarounds, etc. could be accomplished with branches in the belts, and paths from one lane to the other spaced at regular intervals.
Vehicles would consist of a ridged bottom that fit to ridges on the belts, and a mechanism for locking into the sides of the belt. Each vehicle would have a transmitter that would transmit desired speed and direction to the upcoming sections of belt.
Like conventional vehicles, some would be for mass-transit, but family or even individual vehicles would be allowed on the tracks. Track standards and vehicle requirements would be publicly available, to encourage innovation while preserving safety standards.
Emergency and police vehicles would have override codes to allow them to shunt all vehicles to the slow lane, for instance, or stop a particular section of track to apprehend or assist a driver.
The scaffolding for the tracks could double as support for streetlights, telephone lines, cable, and other infrastructure-related items.
Transmitting the desired direction would affect only the branches of track immediately in front of the individual vehicle. Desired speed would be transmitted further ahead and, taking into account the desired speed, the speed of other drivers, minimum and maximum speeds, the tracks ahead would incrementally speed up or slow down to prevent a “jolt” between sections.
Variations in terrain could be mitigated by varying the height above ground level, where the amount of power required to descend and/or ascend would exceed the effort of, for instance, keeping the track level over a small valley or dip in the terrain.
Home and commercial parking would ideally be on roofs or a higher floor. The basic configuration would be a “loop”, where the driver could pull in and set the steering to the inside, so that as other drivers enter, the first vehicle would not venture back out onto the roadway.
By decoupling the energy source from the vehicle itself, more opportunities emerge for alternative power. For example, it would be totally impractical to add a windmill to a car, but having windmills power large sections of track could prove quite reasonable. Likewise for solar, hydro, nuclear or hydrogen energy sources.
By putting the tracks above existing roadways, existing infrastructure can be preserved, at least in the short term, and probably in the long term for transportation to places without track, or for oversized loads.
Accidents between vehicles are prevented because the vehicles cannot hit one another. (an interesting note: drunk drivers would probably do nothing worse than get lost). Accidents involving pedestrians are prevented because the tracks would be inaccessible to pedestrians.
Individual vehicles could be kept very inexpensive, since the majority of the moving parts and electronics would be part of the tracks themselves. The vehicles would essentially be sleds with a remote control for a steering wheel.
Other desirable transportation technologies such as traffic control, traffic prediction and automated driving, all of which are terribly complex for today’s road vehicles, would be much easier given the track system and the data collected, of necessity, by the tracks.
The cost of the tracks themselves, while daunting at first, would gradually be offset by diminished wear and tear on the conventional roadways. Also, tracks could be manufactured offsite, so that construction would be just assembly. Thus, there would be less construction-related traffic delays, and fewer workers needed on-site. Standard track configurations would also benefit from economies of scale not found in conventional roadway construction, which is more constrained by terrain conditions and configurations.
The obvious impediment to switching to a track system would be lack of infrastructure. Ideally, the system would start out as a local transport system, for instance for a large college campus or an amusement park. From there, it could be implemented in a city center, and then gradually spread to connect cities to one another, and then to smaller towns and communities.
In the short term at least, the tracks above would mirror the roads below. Thus, a two-lane road would probably require two lanes of tracks, and the tracks would initially go to those destinations that the roads were going to, as well.
The track itself could be funded by taxes. Initially, of course, there would need to be significant investment of public funds. Ideally, though, registration fees for the track vehicles would provide funding for the maintenance and expansion of the track system. With the use of alternative energy sources (which can now be large and stationary), the fees should be offset by the much lower cost of the vehicles themselves, making the track system financially desirable for individual users.

shadenfroh, May 22 2006

The Roads Must Roll http://www.technove...ontent.asp?Bnum=306
Robert A Heinlein [afinehowdoyoudo, Mar 03 2010]

Twike http://www.twikeklub.ch/technik/index.htm
[afinehowdoyoudo, Mar 03 2010]

Practical limits http://www.leaellio...iles/40766-7260.pdf
Search on "cable" to get to the relevant bits. [mouseposture, Mar 03 2010]


       Multiple vehicles could share one section of track. One vehicle could catch up with another, and share a track. The lead vehicle would then set the pace.
I suppose it's like a train... but imagine that the tracks came up to your house, and you could put your own personal or family vehicle on the tracks. Also, the motive power is in the tracks themselves, not the vehicle.
shadenfroh, May 22 2006

half, May 22 2006

       PRT = personal rapid transit, a broad class of transportation technologies. Sorry. Found the lingo on this site and others and thought it was common.
shadenfroh, May 22 2006

       OK. I'll bite. What's " IHIWPUUA"?
shadenfroh, May 22 2006

       Hint: I would hate it if I ruined the irony for people by defining the undefined acronym.
half, May 22 2006

       my preferred PRT is a Corvette. I like to be green, but I think running a massive moving track would use way more energy than a normal road, since the track has to move a large belt. I'm also not sure that it'd be stable at 70mph. Lastly, I'm not sure you could afford to build this with any reasonable tax increase. Address these concerns for my bun.
sninctown, May 23 2006

       [half] ha! me too.
zen_tom, May 23 2006

       I'll try.
First, you can keep your Corvette and drive it on the road below. However, if you'd also like a vehicle that costs a small fraction of what a Yugo would cost you, but still gets you to everywhere in town, that would be an option, too.
I'm no engineer, so perhaps it would take more energy. I'm not sure of that, though, since you wouldn't have to carry the weight of the engine, etc. Which would take more energy, moving a single large belt with a lightweight "sled" atop it, or moving your entire Corvette? Also, precisely because you don't have to actually move the energy supply, we could resort to cheaper power sources.
As for stability... have you ever ridden a roller coaster? Faster than 70 mph? Same principle.
Lastly, I believe that the infrastructure we already pay for (paved roads) is pretty darned expensive already. In fact, given that tracks can be built on an assembly line before being installed, I suspect that the tracks, if used widely enough, might actually be cheaper than maintaining the roads beneath them. And while there would be a tax, how much would be "reasonable" when it's offset by not having to buy gas, and being able to purchase a much cheaper vehicle?
shadenfroh, May 24 2006

       er... sounds like your not exactly considering any of the engineering facts. Your idea is equivalent of proposing a tiny 12x12x12 inch car to be used as a train to take 40,000 people an hour for a mile.   

       An idea has meaning if you have some hint or clue about HOW your going to achieve this.   

       And you can't call a bus PRT.
pashute, Mar 02 2010

       Let's stop and think for a moment about the series of collisions that's going to happen when just one segment of track breaks down.
sstvp, Mar 03 2010

       Robert Heinlein wrote a story about a belt-city, with incremental speed changes on adjacent belts, starting at near zero at the sidewalk and progressively faster towards the fast-lane.   

       The idea to use a vehicle on the tracks is neat, if it is lightweight and has pedals for off-track use. Like a Twike or even smaller.
afinehowdoyoudo, Mar 03 2010

       I think the tracks would be more popular in the uphill direction, if it was possible to easily switch between road and track
afinehowdoyoudo, Mar 03 2010

       If this were workable, then cable cars would be found somewhere other than San Fransisco. Even railroads prefer to transmit power electrically, and convert to mechanical at the locomotive. There *are* modern systems where centrally generated power's transmitted mechanically to the cars -- airport people-movers and suchlike -- but that only means serious work's been done to establish the envelope within which they're practical: turns out (link) it's impractical for complex routes or for distances longer than a mile.
mouseposture, Mar 03 2010


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