Unitsky String Technologies
24 October 2018
Answer to Artemy Lebedev's studio from SkyWay engineers
Not so long ago, a small critical review (in Russian) of SkyWay technology was published in the "Business-lynch" section at the website of Artemy Lebedev's design studio. The industrial designer of the studio expressed in it doubts about the efficiency of SkyWay transport, although he noted that "the idea looks attractive." It seems to us that the author of the review spent too little time studying the issue, and therefore one can find a large number of inaccuracies and errors in it. In order to reduce these misconceptions in the future to a possible minimum, and, at the same time, with the purpose to explain once again the main elements of the SkyWay concept in detail and in plain words, we will answer some questions posed in the critical review.
How will it be possible to use the space between the supports of SkyWay transport?
And how is the space between the supports of lighting poles in a city used now? What about the space under braces between buildings and masts (trolleybus wires, advertising cross street banners)? It would be easy to mark sidewalks, roadways, lawns under the track infrastructure. And if the track structure and vehicles passing along it are arranged at a sufficient height, then the location of the complex can be combined with ordinary urban facilities. Outside the city, this space will be used as a green zone or agricultural land.
What will happen in case of malfunction, when a cabin with passengers gets stuck at a height of 15 m? Probably, it would be necessary to reach it somehow and, obviously, from the ground.
First of all, the rails can pass both at a height of 68 meters (there is a task to raise vehicles above the ground, to free the surface, but there is no task to rise higher than required this increases the track cost) and 100 meters (for example, if it is a "horizontal lift" between high-rise buildings). At a low height, you can get there from the ground, at a great one this is practically unrealistic. Therefore, all vehicles, firstly, have provision of systems for critical traffic to minimize the likelihood of an off-duty stop on the way; secondly, they are equipped with towing devices (they can be seen in front and behind unibuses), with the help of which a neighboring vehicle can tow a unibus with a breakdown, which will allow to deliver it to the depot and not to block the line.
Movement is possible along fairly smooth, almost straight trajectories. That does not add mobility and maneuverability.
The trajectory is indeed straight "in plan" at string sections of the track structure (i.e., sections with stretching stresses). However, this does not mean that the vehicles are not maneuverable, because they can't turn. The track structure also has transitional non-stressed sections, where a vehicle can take a turn in other words, different types of tracks can be combined to perform various specific tasks.
The minimum turning radii at non-stressed sections is 15 m for passenger monorail unibuses (capacity of 1530 people), 24 m for double-rail ones (capacity of 2560 people). This is comparable with the radii of road bends in the city: typical trajectories have radii from 10 to 30 m depending on the road grade.
If we take lightweight and super-light vehicles with a capacity of 14 people, then their turning radii can be 510 m. This maneuverability is sufficient to drive into each yard, figuratively speaking.
The claimed high speed of 150 km/h on a flexible rail is possible between the supports, while a possible speed on the support is 30 km/h. It means the train will actually move at this speed.
Let's take again a plain automobile analogy. If a car moves at 10 km/h speed before an intersection and on it, does this mean that this is its actual speed of moving around the city? It is obvious that the average speed of movement is important, which will be much higher about 70 kilometers per hour. Also pay attention to the importance of continuous traffic. Automobile transport is suffering from it now. Cars that are capable to run at 180200 km/h, move through the city at an average speed of 1530 km/h (speed limits, traffic lights, traffic jams). Unibuses, like the metro, having no obstacles and moving in a continuous traffic, will provide both a higher average speed and a larger carrying capacity.
Trolleys are driven by electric motors powered by batteries located at the top of the capsules. So that the trains do not stand idle while charging, you will need to change the battery package, which means you need special warehouses where you can store and charge replacement batteries.
The specific solution for the energy supply of vehicles depends on the particular conditions and requirements. The options of solutions to the problem of power supply can be very different: electric accumulators, power from the contact network, hybrid circuits (battery + contact network, battery + onboard generator).
For vehicles with an electric accumulator, recharging is possible at night, between peak hours, during stops for boarding passengers (especially for accumulators with supercapacitors), a unibus with even an electric accumulator can work all day at a certain combination of parameters.
In addition, one should not forget about the almost unique capability of unibuses to use a "gravitational motor" on a sagging structure. The same principle has long been used in the subway. When moving away from the station, a vehicle moves along a small downward slope, and gravity helps it to accelerate. After the middle of the track, on the rise, gravity, on the contrary, starts to slow down the vehicle reducing the necessary energy consumption to drive braking mechanisms. This principle, coupled with low rolling resistance and good aerodynamic shape, allows to obtain very low energy consumption, and, accordingly, removes the need for a large battery or frequent recharging.
The tracks are located quite high, which means that cargo must be lifted for loading to the height of the cargo capsule, and at the destination, lowered back to the ground.
It is even strange to explain anything here: containers are always placed and lifted by cranes. Bulk cargo is poured from a conveyor or a cargo ramp into the unitruck bunker, and then are just poured out in the right place.
Speaking about passengers, they really need to climb and descend along the stairs, on escalators and elevators. Exactly like in the metro. However, a SkyWay urban line costs considerably less than a similar metro line.
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