AT CAD Team/AT Interstate Traveller
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I recently became aware of the Interstate Traveler trough a documentary on Discovery Channel (NextWorld:Trains). However, analysing the design, I found that a number of things could be improved on the Interstate Traveler; namely the parts of the drivetrain/vehicle design, vehicle loading/entry&exit ramp, power source (hydrogen), the use of PV panels, support columns, electrical supply, and the idea of growing plants under the tracks.
First of all, trough the documentary, aswell as a quick look on the interstate traveller's website (http://www.interstatetraveler.us/ ), I noticed that the organisation behind the interstate traveller intented to make the transport system autonomous in operation. The idea herefore is to use a hydrogen fuel cell inside the vehicle, and a (expensive) electrical cable and PV panels for energy generation. I think however that integration of such methods will make the system as a whole very expensive (even if you use Luminescent Solar Concentrators or LSC's in stead of regular PV-panels), and not very cost-efficient. In addition, one will also need to implement batteries, a hydrogen gas production system, ... Finally, the whole will not be that ecological, as the manufacturing of eg PV/LSC panels is still very polluting.
Instead, I believe it would be better to simply use the existing electricity grid instead (fed via the bottom, using a pantograph, see below). It is true that autonomous operation is very important in certain cities (plagued by power interruptions), ie in the developing world. However, rather than setting up all of these seperate systems, it seems better to then simply opt to construct enough own power plants to allow autonomous operation when a Interstate Traveller-system needs to be set up in such cities. This could eg be accomplished using Motorwave wind turbines between the support columns (in addtion with other power plants), using a http://en.wikipedia.org/wiki/Micro_nuclear_reactor, ...
I also noticed another main feature of the original design, namely the ability of the vehicle of switching tracks. However, in the Discovery Channel documentary, it seems that the system uses entry and exit ramps to unload passengers (and/or to keep vehicles from the track, to allow other vehicles to pass). However, the construction of such seperate ramps will quickly become expensive. Rather than using ramps, I think it would be better to simply use either a scissor elevator and a winch system (the first one intented for loading cargo, the other for loading people). This allows the vehicle to remain on the tracks, while loading or unloading cargo or people. The (un)loading would be done at specific locations, destined for this loading/unloading. The stops are marked on the third image using dots. The system would also use a electric system to call the vehicle when people are waiting at the location. The vehicle itself would not remain stationary, but keep driving the tracks around town, on the loop tracks. This prevents obstruction of the track, and the driving around also still allows the vehicles to be spread across different tracks across the town, to reduce pick-up/drop-off time. The large track around the loop track then allows vehicles to go off/unto different loop tracks. The software required for such a task could be easily created; there are eg already car-systems that are similar (see http://imara.inria.fr/lara , ...). Any excess vehicles circling the track would automatically return to the station.
Next up is the design of the vehicle and the cable tracks themselves which, at present, are designed on an expensive manner. Rather than using 2 electrical cables, it seems better to use ordinary steel cables, and integrate the electric cable into a seperate cable, connected via the support columns. Thus, rather than connecting the column cables to the 2 tracks, the line is connected inmediatelly to the vehicle. This can be done using an upside-down pantograph (http://en.wikipedia.org/wiki/Pantograph_(rail) ) connected to the back-end of the IT (to not obstruct the loading bay; see below). The electrical cable itself would need to be placed directly beneath one of the rails, again to not obstruct the loading procedure. The (un)loading would happen via the vehicle floor; the floor would need to slide open at the moment of (un)loading.
For the propulsion, the AT interstate traveller design uses 2 propellers connected to a single AC-electric motor, mounted at the center (back) of the vehicle. Two belts are mounted on the motor's axle, each to one of the ducted propellers at the side. It is hence similar to an airboat, with the difference that 2 propellers are used instead of one (this increases efficiency as the airflow is then uninterrupted by the vehicle). Propellers were chosen instead of the magnetic levitation/propulsion on the original AT interstate traveller for various reasons:
- first, the system is relatively cheap (in comparison to maglev-propulsion)
- secondly, it's easy to mount (no driveshafts needed connecting motor and propeller); if a regular electric motor was used to propell the vehicle using the wires (similar to a cable car) this would be a considerable problem, and extra strengthening of the frame would be needed.
- the only downside is a slightly lower efficiency (than using wheels), atleast when the weight has not been taken into account, and a relative amount of noise. However, the duct around the fans would considerably lower the noise.
In addition to using a scissor elevator or winch-system, the load the vehicle can transport will also need to be standardised (ie 1 or several europallets, see http://en.wikipedia.org/wiki/Pallet , ...). This is needed to facilitate loading/unloading from or into conventional freight vehicles (ie freight trains, CarGoTram, ... ). A rail would also need to be layed to the train stations. Connection to the station would allow easy transport of cargo to otherwise difficult to reach locations within the city (with conventional vehicles). In addition, it would reduce traffic as the IT uses its own "plane" of transportation, hereby not reducing the capacity of conventional roads.
Regarding the design, the aerodynamic properties may still be improved. The fact that it's quite "top-heavy" would make a lower and sleeker form advisable. However, the change in design should still maintain the ability of the undercarriage to change the track. Rather than having "legs" connected to the lines, the vehicle would lay just over and below the lines. The ends would be somewhat bullet-shaped.
For the support columns, I believe it would be best to consider the options already present within the city. Rather than constructing entirely new columns, the top-section (with the lines, ...) of the columns can probably often be placed on existing infrastructure (ie brick houses, bridges, ...) This would reduce the cost.
Finally, the growing of plants between the columns is best discarded. This as there would probably be a lower yield due to shade from the columns/lines, ... aswell as because of exhaust fumes from cars on the road (the columns will probably often be placed very close to roads). Also, possible organic produce (when growing crops) can probably not be eaten due to the same reason. Maintenance of the plants between the columns can also form a problem.
