Downsides to High Speed Lifts?

#31

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11/3/09 at 11:24am

Walt
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Quote:

Originally Posted by Bode Klammer

A friend who who worked at Intrawest once told me that the difference in capacity among detachable quads, based solely on the loading zone, was as much as 30%. Fixed grip quads are all worse than that.

Everything I've read puts HS lifts at about 95% capacity and fixed grips at around 80% capacity.

For instance, http://www.skiliftforum.com/index.php?showtopic=2334&st=0&p=29599&#entry29599
and
http://en.wikipedia.org/wiki/Chairlift (see efficiency under terminology)

I have a hard time believing that Intrawest would allow a HSQ to operate at 65% efficiency.

#32

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11/3/09 at 11:27am

crgildart
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Quote:

Originally Posted by ramzee

Also worth noting that most punters dont actually take many more runs due to a high speed..... they get their runs in more efficiently, get tired more quickly, then go to the lodge and spend more money there... good for the corporation.

Or get hurt while skiing past tired and try to sue the resort.

Smell that? Winter's coming!

#33

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11/3/09 at 11:35am

iWill
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The problem is, the punters are not the ones lining up at 8 am on the powder days. The efficiency of loading increases to near 100% when you've got aggressive skiers and a singles line.

#34

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11/3/09 at 11:48am

tylrwnzl
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Quote:

Originally Posted by iWill

The problem is, the punters are not the ones lining up at 8 am on the powder days. The efficiency of loading increases to near 100% when you've got aggressive skiers and a singles line.

I love singles lines, I don't know what I'd do without them.

Skiing combines outdoor fun and knocking trees down with your face. ~Dave Barry

#35

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11/3/09 at 11:55am

Walt
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Quote:

Originally Posted by tylrwnzl

I love singles lines, I don't know what I'd do without them.

NFOPD. (c:

#36

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11/3/09 at 12:04pm

tylrwnzl
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Very few of my friends ski, and even less can keep up with me, only one to be exact. And he is usually busy so yep, I'm the lonely guy riding the quad chairlift by himself.

Skiing combines outdoor fun and knocking trees down with your face. ~Dave Barry

#37

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11/3/09 at 1:54pm

Bode Klammer
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Quote:

Originally Posted by Walt

Everything I've read puts HS lifts at about 95% capacity and fixed grips at around 80% capacity.

For instance, http://www.skiliftforum.com/index.php?showtopic=2334&st=0&p=29599&#entry29599
and
http://en.wikipedia.org/wiki/Chairlift (see efficiency under terminology)

I have a hard time believing that Intrawest would allow a HSQ to operate at 65% efficiency.

You are right that Intrawest wouldn't tolerate a detachable that was only 65% efficient. That's why they were reworking the loading zone, and that's how the conversation came up. OTOH I don't believe that there's a fixed grip quad anywhere that runs at 80% of its nominal capacity if you measure that at 6 seconds per chair. I doubt any fixed grip quad fills 80% of the seats unless it's running quite a bit slower than 6 seconds. It's interesting that one of the links you posted shows a range of capacities based on loadng rates of 6 to 9 seconds per chair. A fixed grip filling 80% of the sets every 9 seconds has less than 60% of the capacity of a detachable fllling 95% every 6 seconds. For lifts with well designed loading zones, that sounds about right.

BK

#38

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11/3/09 at 2:49pm

iWill
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Quote:

Originally Posted by Bode Klammer

A fixed grip filling 80% of the sets every 9 seconds has less than 60% of the capacity of a detachable fllling 95% every 6 seconds. For lifts with well designed loading zones, that sounds about right.

BK

No it doesn't. The 80% efficiency is taking into account the need to vary the speed, deal with stops, etc. You're trying to apply that on top of a slower speed. You're double-stating the efficiency drop.

#39

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11/3/09 at 4:27pm

crgildart
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What's so hard about the concept that moving more people up the hill faster results in a faster moving line?

Smell that? Winter's coming!

#40

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11/3/09 at 4:43pm

jahroy
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Quote:

Originally Posted by BushMogulMaster

The industry standard capacity for a quad is 2400pph (people per hour), regardless of whether it is detachable or fixed grip... it is rare to see a detach with a capacity higher than 2400pph.

according to skilifts.org the old shirley lake quad at squaw had a capacity of 3,000 pph...

it got replaced by a 6-pack two years ago!

#41

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11/3/09 at 4:52pm

iWill
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Quote:

Originally Posted by crgildart

What's so hard about the concept that moving more people up the hill faster results in a faster moving line?

Um, nothing other than it isn't so.

If you have a fixed grip quad and a detachable quad both with a capacity of 2000pp/hr. Give the detachable quad 20% more efficiency in loading. The mountain is busy, and there is always a line. The detachable quad moves people up in 6 minutes, the fixed grip in 12 minutes. It takes 4 minutes to ski back down. The skiers on the faster lift will be back in line before the skiers on the slower lift unload. If the line starts at 5 minutes for the fixed grip and 4 minutes (20% less) for the detachable, skiers will be back in line every 14 minutes for the detachable and every 21 minutes for the fixed grip. The lines for the detachable will get longer than the lines for the fixed grip. Even with the 20% more efficiency, you will spend MORE time in line and LESS time on the lift.

You only get more time on the mountain and less time in line when the lift is running below full capacity.

Further, you are mistaken in assuming that a detachable quad has a "faster moving line". The quad gains efficiency in loading because it doesn't need to slow down for less skilled skiers...but it can't do that if the skiers have to shuffle out in less time. The time it takes skiers to move into loading position is the limiting factor. You can't magically increase that speed. People need the same 9 seconds to get in line.

#42

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11/3/09 at 4:59pm

crgildart
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Quote:

Originally Posted by iWill

People need the same 9 seconds to get in line.

Haven't you seen the lifts with conveyer belts that folks stand on side by side to get pulled in to place for the chairs? I know they don't have them everywhere yet, but that alleviates that factor. I'm not talking about how long or short the line gets. It still moves at the speed that people go up the hill. If you are moving people up the hill at a faster rate the line moves faster.

Smell that? Winter's coming!

#43

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11/3/09 at 5:10pm

sjjohnston
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IWill is correct that - when there is a line - the speed that the lift runs in the air isn't the limiting factor, but the rate at which people load is the limiting factor. If people load at the same rate on an accelerating chair vs. a fixed-grip, and you keep every other variable constant, the people on an accelerating lift will just trade less time in the air for more time in line, on an exact one-minute-for-one-minute basis.

But: accelerating lifts do actually load people faster. In some cases much faster. Six-packs on a fixed grip lift are impractical, but are a piece of cake on an accelerating lift (kind of: you're still dependent on the arithmetical skill required to add up to six). I believe you can run an accelerating six-pack with the chairs slightly tighter (time-wise) than a fixed-grip quad, which means you can increase the loading rate by more than 50%.

#44

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11/3/09 at 6:45pm

Walt
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Quote:

Originally Posted by crgildart

What's so hard about the concept that moving more people up the hill faster results in a faster moving line?

Rope speed has nothing to do with how fast the queue moves.

A rocketship that comes by once a decade and takes only one passenger moves very fast, but the queue moves slowly. A subway train that comes by every 5 minutes and has enough seats for everyone moves slowly in comparison, but you never have to wait very long.

The two ideas are independent. Capise?

#45

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11/3/09 at 6:49pm

crgildart
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Quote:

Originally Posted by crgildart

What's so hard about the concept that moving more people up the hill faster results in a faster moving line?

Quote:

Originally Posted by Walt

Rope speed has nothing to do with how fast the queue moves.

A rocketship that comes by once a decade and takes only one passenger moves very fast, but the queue moves slowly. A subway train that comes by every 5 minutes and has enough seats for everyone moves slowly in comparison, but you never have to wait very long.

The two ideas are independent. Capise?

'that's why I said "more" people at a faster speed... to include the premise of a larger capacity seat also moving up the hill faster.. Capise?

Smell that? Winter's coming!

#46

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11/3/09 at 7:41pm

Walt
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Right. Moving more people by, say, replacing a double with a quad makes the queue move faster. Moving the chairs faster doesn't make the queue move faster.

Have we beat this dead donkey enough? It's the quad part of "high-speed detachable quad" that makes most of the difference.

#47

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11/3/09 at 8:19pm

jahroy
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i've noticed that high speed lifts that are always empty are cool.

#48

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11/3/09 at 8:37pm

splitter
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more people skiing = more chopped worthless crud

chopped worthless crud = tired

tired = beer

but I s'pose I'm just not that core...

#49

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11/3/09 at 11:49pm

prickly
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Fascinating discussion.

It's "capisce," actually...

Control. Freedom is control.

#50

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11/4/09 at 5:18am

catskills
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You folks got most of the details here in this thread. Good job. Most people don't understand that fixed grip quad vs HS quad have the same capacity.

The easiest way to explain this to someone is 6 Seconds to load/unload a chair is the standard for both fixed grip quad or HS quad. Fixed grip quads have twice the chairs and twice the people hanging in the air, which BTW makes lift evac twice as long. Measure it with you watch some time when your standing in line.

Fixed grip quads are better than HS speed quads when there is a long line on a warm day. Reason: you get to sit on the chair twice as long and spend less time standing in line.

NY state is very restrictive on cable speed as well. I know the fixed grip quads at Jackson Hole travels faster than the ones here in NY State. The Jackson Hole fixed quad just have more space between the chairs.

Also note that a fixed grip double in NY State and most states can legally travel faster than a fixed grip quad. When comparing lifts you got to take all this into consideration.

For a real people mover (high capacity) you can't beet a high speed six pack. They beat an 8 seat gondola for capacity.

As already pointed out the HS detachable quad does have higher capacity than fixed grip quad because of less stoppage time on HS detachable quad, which are easier to load/unload. Add conveyor belts and you get even higher capacity.

Math is fun.

#51

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11/4/09 at 5:43am

Bode Klammer
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Quote:

Originally Posted by iWill

The 80% efficiency is taking into account the need to vary the speed, deal with stops, etc. You're trying to apply that on top of a slower speed. You're double-stating the efficiency drop.

Maybe, but I've never seen chair lift efficiency defined, so you can't know for sure. from my own observations, it seems pretty unlikely that you can run a fixed grip at full speed and fill 80% of the seats at the same time. Some of that is because a lot of fixed grip chairs have somewhat disorganized queues, but mostly fixed grip quads are hard to load.

BK

#52

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11/4/09 at 5:44am

prickly
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All interesting stuff. Throw this into the mix, for us poor Euro types: chair loading is piss poor here, I'd guess poorer on high speed lifts than on fixed ones. What's the effect of that on overall performance? Stand in line for a six pack in Europe and count how few chairs go up fully loaded. Breaks a skier's heart.

Control. Freedom is control.

#53

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11/4/09 at 5:45am

Bode Klammer
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Quote:

Originally Posted by splitter

more people skiing = more chopped worthless crud

chopped worthless crud = tired

tired = beer

but I s'pose I'm just not that core...

More high speed quads = more people skiing whining to the mountain manager = more grooming = fail

BK

#54

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11/4/09 at 6:37am

splitter
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Quote:

Originally Posted by Bode Klammer

More high speed quads = more people skiing whining to the mountain manager = more grooming = fail

BK

trust me,

I'm not the guy worried about grooming...

I just don't ski worthless chop...

'course, I don't usually get on high speed quads, or fixed grips, or carpets, or t-bars or whatever all that stuff is...

#55

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11/4/09 at 7:11am

Walt
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Quote:

Originally Posted by catskills

Fixed grip quads have twice the chairs and twice the people hanging in the air, which BTW makes lift evac twice as long.

Another consequence of having twice the people is that the rope bears twice the weight. This make for a practical limit on how long a fixed-grip lift can be. Detachables lifts can span longer distances due to the reduced weight on the rope.

Put a checkmark in the "plus" column for HS chairs.

#56

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11/4/09 at 7:30am

Walt
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Quote:

Originally Posted by catskills

NY state is very restrictive on cable speed as well. I know the fixed grip quads at Jackson Hole travels faster than the ones here in NY State. The Jackson Hole fixed quad just have more space between the chairs.

Also note that a fixed grip double in NY State and most states can legally travel faster than a fixed grip quad. When comparing lifts you got to take all this into consideration.

Lift laws vary state-by-state, but many (most? all?) are based on the ANSI standard. The max rope speed according to ANSI is:

Fixed-grip single chair: 600 ft/min
fixed-grip double chair: 550 ft/min
fixed-grip triple chair: 500 ft/min
fixed-grip quad chair: 450 ft/min

Every time you increment the butt-count, the rope speed must drop by 50 ft/min. You still come out ahead capacity wise, since rope speed is independent of capacity*.

Most lift operators run the rope a bit slower than the max to make it easier on the clientelle.

*Actually, for a specific lift with a specific chair spacing, running it faster will increase the number of chairs per minute, and thus increase capacity. However, at design time the engineer takes rope speed, chair spacing and loading interval into account to make a system with the desired capacity. The faster speed at lower butt-count won't help to increase design capacity.

#57

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11/4/09 at 7:51am

crgildart
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Quote:

Originally Posted by prickly

Fascinating discussion.

It's "capisce," actually...

Indeed, I applaud myself on this cast. I was just fussing about wanting a longer, slower ride per vert feet because I'm lazy and out of shape

Smell that? Winter's coming!

#58

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11/4/09 at 8:00am

prickly
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Maybe this could morph into a thread about which chairs are best for suntanning, given exposure/length of ride. We have a great one up at 3,000 meters, painfully slow, but very sunny in Spring.

Control. Freedom is control.

#59

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11/4/09 at 8:13am

Walt
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Quote:

Originally Posted by crgildart

Indeed, I applaud myself on this cast. I was just fussing about wanting a longer, slower ride per vert feet because I'm lazy and out of shape

Most resorts have benches near the unloading area for the snowboarders to strap in. You could always just sit down on one of those for 5 minutes after each lift ride. (c:

Agree that HS lifts wear me out faster - sometimes I have to quit after only 7 hours.

#60

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11/4/09 at 12:31pm

BushMogulMaster
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Quote:

Originally Posted by Walt

Another consequence of having twice the people is that the rope bears twice the weight. This make for a practical limit on how long a fixed-grip lift can be. Detachables lifts can span longer distances due to the reduced weight on the rope.

And while we're talking wire ropes, let's talk about lay. Most detachable lifts use lang-lay wire ropes, while most fixed grips use a regular-lay. Because a regular lay has the wires of the strand laid opposite the direction of the stands upon the core, there is more resistance to grip slippage.

If anyone really wants to have some, uh, "fun" this season, study the haul ropes of different lifts as you ride. You'll notice four basic types:

Right Regular Lay (strands are laid around the core to the right, but wires are laid around the strands to the left)
Left Regular Lay (opposite above)
Right Lang Lay (strands are laid around the core to the right, and wires about the strands also laid to the right)
Left Lang Lay (opposite above)

Well, maybe that's not "fun" to all of you. But I do it............

You'll also notice most fixed grips use a 6x19 wire rope, while detachables use a 6x37. But I'm gonna quit while I'm ahead...

~Patrick Torsell
Director, Mogulskiing.net

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