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So I've finally found something that has brought me to this rabbit hole of worldbuilding. I've been doing some future planning for an expansive subterranean facility that would require heavy cargo transport and have been looking at options for such.

One of the concepts I'm considering is a large crane system from a ground-level intake point that could then lower down the cargo via cable/crane/gantry winch to whatever depth it is going. Then I began wondering about what other utility could be had from such a shaft and recalled this: Yamatau Helical Elvator

D6 Helical Elevator

In practice, this shaft would be a secure area with the area around it being for movement of authorized personal so it isn't a thoroughfare. Setting aside the security risk that a shaft like this could prevent in the event of an incursion into the facility, and the difficulty of locking down sections of the facility if need be, how well would this sort of system work? Operating on the assumption that security issues are not an issue or have been seen to, how practical would this be?

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    $\begingroup$ Spiral loops are a very common design in railways. $\endgroup$
    – AlexP
    Aug 27, 2020 at 14:33
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    $\begingroup$ ...and even more common in parking ramps. $\endgroup$
    – user535733
    Aug 27, 2020 at 16:06
  • $\begingroup$ @user535733 And even more common in stairwells $\endgroup$
    – DKNguyen
    Aug 27, 2020 at 17:51
  • $\begingroup$ And if you make it a cog railway (as for instance many mountain railways in Switzerland), you can have a much steeper grade. So the distinction between elevator and railroad becomes fairly academic. $\endgroup$
    – jamesqf
    Jun 5, 2021 at 18:29

5 Answers 5

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Ladders/vertical elevators

  • Smallest footprint
  • Shortest travel distance
  • But requires you to produce enough force to directly lift your own weight (if you don't use a counterbalance).

Stairs/Escalators

  • Basically just ramps
  • Larger footprint than a ladder
  • But less force required, at the expense of longer travel distance

Spiral stairs/elevator

  • Just a ramp wound up onto itself to cram more length into a smaller footprint

  • More length means you have a shallower slope for the same vertical distance which means less force required at the expense of even longer traven distance. So good for very heavy loads or if you have limited propulsion and when you cant'use a counter balance.

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    $\begingroup$ The counter balance is what makes elevators efficient (and why you don't directly lift your own weight). "The calculation for the weight of the counterweight is the car deadweight (balance), plus a percentage of the rated load — often referred to as the “overbalance.” Traditionally, the overbalance value for most installations was 40-42.5%. For newer systems, especially those using permanent-magnet AC gearless machines, the overbalance is commonly 45-50%." (Source) PseudoSim, I'd recommend you read that article. $\endgroup$
    – JBH
    Aug 27, 2020 at 4:39
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    $\begingroup$ Elevator also has counter-ballance in form of stairs going backwards. But for heavy loads (>10 tons) and long distances counter-balance is not a good option (it just wouldn't give any advantage - you still get several tons off-ballance for different reasons). For such a cases "self-propelled lifts" are more suitable. And for them straight or spiral ramp seams to be reasonable. $\endgroup$
    – ksbes
    Aug 27, 2020 at 10:24
  • $\begingroup$ Ah, yeah. I forgot about counter balances in elevators. $\endgroup$
    – DKNguyen
    Aug 27, 2020 at 15:26
  • $\begingroup$ @JBH: couldn't the counter-balance run down the center of the spiral, which seems to be dead space in this design? $\endgroup$ Aug 27, 2020 at 15:46
  • $\begingroup$ @TedWrigley There are a number of ways the counter-weight could be designed. It could run down the center. It could run along the bottom of the rails themselves. It could be entirely outside the hole (although that would present some other challenges). Running it down the center would require the counter-weight to be the lowest mass (highest efficiency). Running it under the rails would require a larger counter-weight (because some of the weight is displaced by the horizontal force component of the angled rails), but would free the center of the shaft for other purposes - like cave diving :-). $\endgroup$
    – JBH
    Aug 28, 2020 at 3:03
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You might want to glance at the spiral railroad tunnel at Kicking horse Pass in Canada.

writeup here

Of course this is about a mile diameter, which is much larger than your shaft, but that's because of the size of a train and its inability to get around a very tight curve.

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  • $\begingroup$ Spiral loops are a very common design in railways. Usually in the open, not in tunnels. $\endgroup$
    – AlexP
    Aug 27, 2020 at 14:33
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An important consideration is how are you going to actually move the elevator? The spiral rail tunnels mentioned are effectively self-powered - the train provides the motive force. Elevators on Earth are generally straight, because the carriage is moved by an external power force through cables, and cables like to be straight. The Eiffel Tower has non-straight elevator shafts, and there was significant engineering effort that went into making them work.
A spiral elevator is going to pose difficulties for the traditional cable system, but maybe you could have two of the rails be powered, and have a motor on the car? It will be heavier than a normal elevator, and have less cargo capacity for the same amount of power usage.

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Gearbox train cars:

My son used to have a certain brand of toy trains that used gearbox arrangements to allow the self-propelled trains to climb slopes. The wheels were there just to hold up weight. Your system could have a track with threads so the cars could grab ahold and climb the sides of the shaft. There could be a slot in the side of the wall to hold it in place, or there could be a central shaft that the cars are tethered to.

Similarly, a central shaft could be threaded and either used to mesh with a vehicle's gearbox, OR the central shaft could rotate, pushing your car up and down a spiral ramp in your shaft.

I'm not making any claims to what is more efficient, but this could work. If your goal is to have a spiral track going up a shaft, because it looks super-cool for your world, than it is an alternative. Geotrax tracks

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FYI, there is a real-world, operational helical-track hydraulic elevator at the auditorium at Apple's headquarters. It rotates 171 degrees to allow entry and exit via the same door, despite the door opening on the floors being in different places. The architects claim it's the first in the world. 1, 2

As for incline elevators, they're more common, since they can still be implemented using counterweights on tracks. The main train station here in Zurich has some.

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