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Common misconception?

post #1 of 17
Thread Starter 
Please forgive me if this topic has been discussed in the past, but I couldn't find any references to it when I searched.

I often find statements like this in the media and from other skiers: "High-speed lifts that whisk four or six persons per seat up a slope at speeds of 1000 fps have increased the density of skiers on the slopes."
The thesis is that high speed lifts have something to do with uphill capacity. It seems to me that they do not.

Follow me here; the key to putting people on the slopes is the frequncy at which chairs are loaded at the bottom and unloaded at the top of the lift. That frequency is the same whether or not the lift is high speed or fixed grip. It is true that in the absence of significant lines the high speed chair gets individuals to the top faster and increases time on the run, but it does nothing to increase the number of people on the run if the chairs are all full. On a busy day lift line length should be shorter on a fixed grip because more people are hanging in the air at one time than on a high speed chair.

I love high speed lifts, and the claim that they increase the number of skiers and boarders on the hill over a fixed grip lift of similar size (ie. quad for quad) just doesn't compute for me. I believe that the reason some slopes are becoming more crowded is that old style double chairs are being replaced by quads or sixpacks which will double or triple the rate of loading and unloading bodies whether they are high speed or fixed grip.

I know that this is a silly post, but what else do we have to do here in the PNW?
post #2 of 17
What you are forgetting is that non-fixed chairs sometimes take longer to load because you have to wait for the next chair.
post #3 of 17
Quote:
On a busy day lift line length should be shorter on a fixed grip because more people are hanging in the air at one time than on a high speed chair.
At any moment in time, assuming the chairs are the same distance apart on the two types of lifts, shouldn't there be an identical number of people in the air? Faster travel speed means lines should be shorter as each trip up takes less time.

I don't know about skiier density, but I enjoy faster lifts on powder days, the stronger skiiers get more runs in.
post #4 of 17
As long as the lift-line density is low, I'm happy.
post #5 of 17
Thread Starter 
Quote:
Originally Posted by gramboh
At any moment in time, assuming the chairs are the same distance apart on the two types of lifts, shouldn't there be an identical number of people in the air?
I've never actually measured, but by personal observation it looks like fixed grip chairs are much closer together. They don't slow down at the loading and unloading areas, so their interval has to be figured by the frequency that they come to the load line, giving skiers enough time to get ready. The high speed lifts do the same with similar frequency, but when they go to warp speed they increase their interval, arriving at the top at the same frequency as leaving the bottom, but spread out more in the middle.
post #6 of 17
Thread Starter 
Quote:
Originally Posted by Ghost
What you are forgetting is that non-fixed chairs sometimes take longer to load because you have to wait for the next chair.
So you're saying that fixed chairs pick up skiers at a greater frequency than high speed ones? I made my observation on the assumption that there is some magical frequency that somebody has determined that works best for loading, and that it would be the same for fixed and non-fixed grip lifts.
post #7 of 17
Quote:
Originally Posted by pheft
"High-speed lifts that whisk four or six persons per seat up a slope at speeds of 1000 fps have increased the density of skiers on the slopes."
My .45 doesn't hit 1000 fps.
post #8 of 17
fps doesn't matter it is the number of persons per hour delivered to the top of the hill and then devided by the number of choices they have to slide down.
post #9 of 17
4 and 6 seat detachables load at a little slower speed than a 4 pak fixed grip. However detachable the chairs are much closer together at the bottom station. In this way I believe there are far more loadings per minute on detachable than fixed grip for a 4. With a 2 seater the lift may load at a higher speed but only half or maybe a third of the people are being transported.

As well less time on the lift due to higher rope speed than that means more time spent on the hill during the day and less time hanging so now more density.
post #10 of 17
It's feet per MINUTE (fpm), not feet per second (fps). Grizz is right, a bullet travels around 1000 fps, a detachable lift travels at about 1000 fpm.

The detachables load at about the same rate as a fixed grip, because there is a safe amount of time between chairs to get loaded and unloaded. However, they just get you to the top a lot faster. There does not need to be more space on the cable on a detach, because they move slower when loading and unloading, and stack up one right behind the other. However, a 4 person chair takes twice as may people up the hill as a 2 person, and a 6 pack, 3x as much. So a fixed quad would dump people off at the top at about the same rate as a high speed quad.
post #11 of 17
Thread Starter 
I got the quote about the 1000 fps from the first link in the post "Ski Law." If the folks that wrote that article are as careful with the rest of the article we should take it with a grain of salt. Thanks for catching it.
post #12 of 17
A high speed 6 will get people up the slope much faster than a slow triple or double.

However, a high speed quad and slow quad have about the same loading frequency, meaning the high speed won't fill up the slopes any faster. The high speed chair will have larger spacing between chairs actually on the lift line. What it does effectively is reduce the amount of time you actually spend sitting in the chair... which doesn't decrease your overall lift time if there's a line, but gets you there faster once you're at the station.
post #13 of 17
I think the general debate is pointless -- we need to compare "skiers per hour" numbers regardless of the chair type. I have seen some pretty fast fixed chairs and some pretty slow detacheables. And a fixed may have 6 seats while the detacheable has 3 (for example). There would be some overlap there. I don't think you can generalize by the type of chair -- the overall "skiers per hour" number is the only thing that matters. That tells you how quickly lift lines move, and how quickly skiers get dumped off at the top, thus filling the slopes.

Craig
post #14 of 17
This whole thing is stupid. All you need to do is count the number of people at the hill. More people at the hill=more people on the slopes. The lifts really don't matter.

Having said that, an argument could be made that high speed lifts transfer capacity from lift lines to the slopes--meaning that less people are lining on line and therefore more people are on the slopes at any given time. However, high speed lifts also attract more people and that effect tends to dominate.
post #15 of 17
The original post is correct that loading speed (number of people loaded per minute) is the limiting factor, and the speed that the lift travels is irrelevant (so long as there's a lift line, anyway). Indeed, if you think a little more about it, compare two lifts that might be put in the same place, one fixed grip, one high speed -- assume they load the same number of people per minute and assume skiers ski down the hill at the same speed whichever lift is there -- the result of using the high speed chair rather than the fixed-grip is that people spend the same amount of time on the hill, a little less time sitting in the chair and a little more time standing in line.

BUT -- fixed grip chairs do load faster, and they stop less often. The chair is moving much, much more slowly in the loading area, which makes it easier for people to get on, even if the space (in time) between chairs is shorter than with a fixed-grip chair. Trying to run a fixed-grip six-pack at normal speed would be well-nigh impossible. Because the chair doesn't have to slowed down for kids and beginner, and because there are fewer loading and unloading mishaps, the chair runs more continuously.
post #16 of 17
A little more on the first paragraph:

Say you've got a quad chair (fixed-grip or detachable). Say you load a chair ever 6 seconds. That 40 people per minute. If you get at the back of a lift line and there are 200 people in front of you, it will take five minutes until you get on the chair (assuming no snowboarders insist on riding two to a chair).

Okay ... lets say there are 2,000 people skiing on this chair. For simplicity, let's say they all take 20 minutes to ski from top to bottom.

Say the lift is a fixed-grip, and it take 20 minutes to ride up. At any given moment:
- 200 chairs are in the air on the way up (20 minutes x 10 chairs per minute). 800 skiers are sitting in them.
- 800 skiers are on the way down. They're the same 800 skiers who were sitting in the chair 20 minutes ago. The four who were just unloading then are just reaching the lift line now.
- The remaining 400 skiers must be in the lift-line (there's nowhere else for them to go). So there's a 10-minute lift line (it takes 10 minutes to load 400 skiers).

Now say the lift is detachable and it takes 10 minutes to ride up. Say that it loads at the same speed (whether or not that's the case in the real world) and that the skiers ski at the same speed. At any given moment:
- 100 chairs are in the air, with 400 skiers in them.
- 800 skiers are on the way down, just like in the first example. Now, though, they're the 400 skiers who were in the air 10 minutes ago, as well as the (different) 400 skiers who were in the air 10 minutes before that.
- 800 skiers are now in the lift line, and the line has lengthened to 20 minutes.


Another way to look at it:
If the lift loads 40 skiers a minute, and there are 2,000 skiers, it takes 50 minutes to cycle through the skiers one time. No matter what you do, it still takes 50 minutes. If you take 10 minutes out of the ride up, and keep the ski down the same length, the 10 minutes has to get taken up somewhere. All that's left is the line.
post #17 of 17
Also: the physical distance between the chairs on the cable isn't the limiting factor. You could mount chairs ever two feet if you wanted.

The limiting factor is how quickly people can load. Slow moving chairs are easier to load (even if they are much closer together, physically, in the loading area). The result is you can run detachable chairs closer together, in time, than fixed-grip. They may wind up farther apart in distance on the cable, but that's not really relevant.

For an extreme example, consider a mid-size gondola. At loading, they're typically moving very slowly, almost touching each other. Ten people can hop in each, with gondolas leaving every few seconds. Imagine ten people trying to scramble into a fixed-grip gondola.
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