12 replies to this topic

[snoloco]

A detachable lift always goes faster than a fixed grip, but has less chairs on the line. If a fixed grip lift is upgraded to a detachable with the same capacity, what is the effect on lift lines. The skiers are making faster round trips, but less chairs means less people are sitting on the lift. What happens in terms of distribution of skiers on the mountain where they can be skiing down, on the lift, or in line if a fixed grip quad is upgraded to a detachable quad of the same capacity?

[DonaldMReif]

Typically, detachables tend to have slightly higher capacities since the chairs can be more closely spaced (although they are technically farther apart due to the higher speeds). And even between detachables, this can be seen when comparing quads to six packs. I mean, the original Mountaintop Express quad had 113 chairs. The current six pack has 92 chairs. The original Colorado SuperChair quad had 153 chairs and the current six pack has 132. But the newer lifts have larger chairs so the extra two people that can sit in each chair make up for the loss of chairs.

[DonaldMReif]

But there is usually some increase in capacity sometimes. I think fixed grip quads usually can have about a 2,400 pph capacity at best while many high speed quads I've been on typically have a 2,800 pph capacity.

[2milehi]

Uphill capacity (people per hour) is defined as

people per carrier * 3600 seconds
time between carriers (seconds)

Note that speed is not directly in the equation. On fixed grip lifts more carriers are needed and that adds extra load to the towers.

So if a detachable is rated for 2400 PPH and a fixed grip is rated for 2400 PPH, lift lines would not change. There would be more people in the air on a fixed grip.

This post has been edited by 2milehi: 26 October 2014 - 06:36 PM

[Backbowlsbilly]

There's a fixed grip six pack in Austria that has a capacity of 2,971 pph. It's called the Sommerberg and is pretty short, I believe that it is in Zillertal, Austria. Sorry the picture may be hard to read.

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This post has been edited by Backbowlsbilly: 26 October 2014 - 07:01 PM

[ccslider]

snoloco, on 26 October 2014 - 03:35 PM, said:

A detachable lift always goes faster than a fixed grip, but has less chairs on the line. If a fixed grip lift is upgraded to a detachable with the same capacity, what is the effect on lift lines. The skiers are making faster round trips, but less chairs means less people are sitting on the lift. What happens in terms of distribution of skiers on the mountain where they can be skiing down, on the lift, or in line if a fixed grip quad is upgraded to a detachable quad of the same capacity?

Back to the original question. In general, if the capacity of the lift is the same but the detachable has 50% fewer carriers and operates at twice the speed, then on a capacity day, the wait queue will be twice as long. So, same number of skiers on the slopes, fewer passengers riding the machine, more passengers waiting in line.

[Peter Pitcher]

At first it seems simple, same capacity same lift line but then with half as many people hanging on the lift where are the other half? In the lift line, but not twice as many because the same number are on the trails. But wait a minute, with a detachable you can make more runs, you might get a little bit more tired and not ski down quite as fast, therefore more people on the trails, not simple at all

[teachme]

OK, seems simple to me. Needs to be broken down into three situations. One when the resort is fully lift limited, meaning lineups at both FG and HS lifts. Two a transition point when no lineup at the FG but short lineups at the HS. Three no lineups at either FG or HS

Some assumptions:
- Skiers take the same time going down in either situation (ie long lift lines do not make them ski slower)
- Situation is dynamically stable (not first run of the day)
- Number of skiers in slope complex (skiing, in line, and on lift is stable)

If fully lift saturated then same number of skiers on the slope at all times no matter what the lift - FG or HS. Basically same number of people unloading every hour and taking the same time to ski down. The other people are in the lift 'complex' (lift line and on chairs). On a FG the line will be shorter but more will be on the lift. On a HS the line will be longer but fewer on the lift. The key here though is that the time from entering the lift line to the time of unloading at the top will be the same in either situation if fully saturated. FG will be less time in line but longer on the chair. HS will be longer in line but less on the chair. Sum of time will however be equal.

If not lift limited at all then no time in line so HS will allow more runs.

As the lift approaches capacity, situation two, the number of skiers on the slope and in line with a HS lift will reach the maximum more quickly than with a FG, Basically same number of skiers making more runs per hour each. At this point there is a transition period where FG lift saturation is still being approached but HS is already saturated. There may be short lift lines on a HS but not on a FG. In this case the HS lift line and chair time is less than the FG time. This can be explained by each individual skier having more runs so HS at saturation. With the same number of skiers on a FG slope complex there will be fewer on the actual slope due to more being on the chairs, but not every chair will be full (say 90% capacity). With a FG the slopes will have fewer skiers when below capacity compared to the HS (more skiers on chairs but not every chair full).

Again, the real key I think is that when fully saturated lift line + ride time is equal for FG or HS. When not fully saturated then more runs on a HS. At the start of the transition period when the HS gets its first line to the end when the FG gets its first line the number of runs an individual skier can do per hour will slowly fall from [ (ski time + HS ride time)/ hour ] to [ (ski time + FG ride time) / hour ]

Once the FG has a line, then the number of runs per hour for an individual skier does not depend on the lift being FG or HS. Before that point then an individual skier can do more runs per hour on a HS.

If anyone wants I can ask one of the maths faculty down the hall for some real formulas :) but seems right to me.

TME

This post has been edited by teachme: 29 October 2014 - 01:20 AM

[Peter Pitcher]

teachme, on 29 October 2014 - 12:47 AM, said:

OK, seems simple to me. Needs to be broken down into three situations. One when the resort is fully lift limited, meaning lineups at both FG and HS lifts. Two a transition point when no lineup at the FG but short lineups at the HS. Three no lineups at either FG or HS

Some assumptions:
- Skiers take the same time going down in either situation (ie long lift lines do not make them ski slower)
- Situation is dynamically stable (not first run of the day)
- Number of skiers in slope complex (skiing, in line, and on lift is stable)

If fully lift saturated then same number of skiers on the slope at all times no matter what the lift - FG or HS. Basically same number of people unloading every hour and taking the same time to ski down. The other people are in the lift 'complex' (lift line and on chairs). On a FG the line will be shorter but more will be on the lift. On a HS the line will be longer but fewer on the lift. The key here though is that the time from entering the lift line to the time of unloading at the top will be the same in either situation if fully saturated. FG will be less time in line but longer on the chair. HS will be longer in line but less on the chair. Sum of time will however be equal.

If not lift limited at all then no time in line so HS will allow more runs.

As the lift approaches capacity, situation two, the number of skiers on the slope and in line with a HS lift will reach the maximum more quickly than with a FG, Basically same number of skiers making more runs per hour each. At this point there is a transition period where FG lift saturation is still being approached but HS is already saturated. There may be short lift lines on a HS but not on a FG. In this case the HS lift line and chair time is less than the FG time. This can be explained by each individual skier having more runs so HS at saturation. With the same number of skiers on a FG slope complex there will be fewer on the actual slope due to more being on the chairs, but not every chair will be full (say 90% capacity). With a FG the slopes will have fewer skiers when below capacity compared to the HS (more skiers on chairs but not every chair full).

Again, the real key I think is that when fully saturated lift line + ride time is equal for FG or HS. When not fully saturated then more runs on a HS. At the start of the transition period when the HS gets its first line to the end when the FG gets its first line the number of runs an individual skier can do per hour will slowly fall from [ (ski time + HS ride time)/ hour ] to [ (ski time + FG ride time) / hour ]

Once the FG has a line, then the number of runs per hour for an individual skier does not depend on the lift being FG or HS. Before that point then an individual skier can do more runs per hour on a HS.

If anyone wants I can ask one of the maths faculty down the hall for some real formulas :) but seems right to me.

TME

Not quite so simple, do detachables affect skier behavior? Resort Operators say that they do but everybody knows that they are notorious liars. But what about actual capacity versus theoretical capacity. Everybody knows that a fixed grip quad is going to have a lot of stops. Why would a resort operator elect to buy a detachable versus a fixed grip if the actual capacity is the same? I know that we are dumb...but we are not THAT dumb.

[SkiDaBird]

I think they definitely affect skier behavior. The snow in Peruvian Gulch has been significantly better since the installation of LC and Gad 2.
In relation to why they would buy a detach if the actual capacity is the same, a huge reason is ride time. Peruvian would be a 20 minute ride if it were fixed grip. The 7 minutes was painfully cold on LC if the weather wasn't perfect, so the 3.5 on the HS is much appreciated. It is also much easier to ski Collins Gulch at Alta since the HS was installed since you only have to take 1 lift to ski the whole gulch instead of 2.

[teachme]

Peter, you are right of course that there are really two aspect; the mathematical and the psychological. My argument above was based on the mathematical problem alone. On a re-read I do not think I was as clear as I could have been, but I do think the argument is valid.

Personally my skiing habits change with a HS lift
- Plan my runs less
- Ski faster / more aggressively
- More willing to try new runs and chutes
- Only ski at resorts with (mainly) HS lifts
- Would never buy a seasons at a mountain without a HS (unless that was more than a 4 hour drive)


So, why same HS vs. FG for same pph? Some thoughts:
1 - Legal requirements for max lift capacity?
* Perhaps due to enviro mitigation stuff for example?
2 - Long but less used lift?
* I do not ski Burfield at Sunpeaks as it is a long FG. I would if HS
3 - Increase visits for marketing reasons
* Skier expectations?
* Justify higher lift prices that more than cover cost of HS vs FG lift?
4 - Makes the resort look better to say HS
5 - Increase skier visits
* Skiers happy to be able to lap quicker so come more to the resort / buy more seasons' passes?
6 - Slope can not handle more people?
* i.e. Lift feeds a snow park???
* Higher pph would would overload another slope/lift complex
7 - Increased revenue in restaurants
* Lap more so take more breaks to buy more delicious cinnamon buns at the top of Sunburst Express :)

Just some thoughts from an ex-patroller now living in Dubai :(

TME

This post has been edited by teachme: 05 November 2014 - 12:53 AM

[Andy1962]

So to change up the thought pattern a bit. The real question in the skier's mind is, does the new chairlift fixed grip or high speed, get the skier back to what he/she was doing, faster than the previous old chairlift did? The real time period being measured in the skiers mind is, the time from arriving at the load point of the chair to the time when they stand up out of the chair at the top of the hill. All the skiers cares about, at the lift base, is geting back to what they were doing ie sking or snowboarding. If an old fixed grip, say 6000 feet long, run at 400 feet per minute (15 minute ride time) , is replaced by a high speed quad, running nominally at 1000 feet per minute (6 minute ride time) then all the skier cares about is whether the new chair is being run fast enough to make the lift line disappear faster enough that some of the nine minutes of gained ride time are now in the skier's pocket. If the lineups, because of more tickets sold, or attracting skiers from other parts of the mountain, are now more than nine minutes longer than they were before (when the slower lift was in place) then the skier has lost or has not gained., the ski hill has probably gained because of higher ticket sales. If the lines are always nine minutes shorter with the new chair (compared to the old chair it replaced) , the skier always wins (gets more runs in, in a day). different chair slope lengths as well as different running sppeds of the chair being replaced, will alter the discussions. Just throwing it out there in a different way.

[Kelly]

The owner of Riblet Tramway along with his son developed a nice summary on capacity and its associated factors.
In North America they truly went through the development of single chairs, then double then triple and finally quads.
Although the company has changed names and no longer operates as Riblet Tramway but the webpage is still available: http://www.riblet.com/lift.htm