18 replies to this topic

[nathanvg]

From a skiers perspective, I think most would agree that they prefer HSQ to FGQ, but that is not the point of this post.

I got to thinking about these two lifts and came to realize that FGQ often have a higher true capacity that HSQ. It seems to me that the uphill capacity per hour is not the best capacity metric. I'm not aware of a better one but what is missing from the uphill capacity per hour metric are the effects of the speed of uphill transportation and the number of people on the chairlift at one time.

To illustrate my point, consider the following example:
-Consider two ski areas each with just one lift and similar terrain.
-One has a HSQ and one a FGQ both with uphill capacities of 2400 skiers per hour. (They would also have the same time between chairs loading and unloading)
-Both lifts are the same length.
-The HSQ has twice the line speed of the FGQ.
-Lets say the FGQ has 100 chairs.
-Given this information we can infer that the HSQ would have approximately half the number of chairs (50)

Now lets try to determine the total capacity of the two ski areas. The total capacity is simply the number of skiers on the runs and the number on the lifts. Because the two ski areas have the same terrain and same time between unloading, the number of people on the runs would be the same. Lets say 100 people. The number of people on the FGQ would be 200 (100 chairs / 2 *4 people per chair) The number of people on the HSQ would be 100.

So the ski area with the FGQ would actually support 100 extra people (50% greater capacity resort capacity). Furthermore the FGQ would have a 100% greater lift capacity. This result leads to an counter intuitive situation: If a resort replaces a FGQ that has no line, but is near capacity with a HSQ, the new lift would actually have a significant line. (100 people in the example above)

I realize that the metrics above are easily derived from the standard metrics you see on a ski lift, but is there a single metric I am unaware of that depicts this difference in lifts? Any thoughts?

NOTE: I realize that I have made some assumptions in my figures above, but I think they are realistic assumptions.

[highspeedquad]

I don't believe that that's true, since although there are more people on the lift, people still load and unload at the same interval. Although there may be more people on the FG quad at any given moment, there will be the same amount of people who have completely ridden the lift over a given amount of time. Also, you can manipulate the HSQ easier than a FGQ, so you can have a capacity of 2800 on a HSQ but only 2400 on a FGQ.

[Kelly]

nathanvg is kinda right.
Those 100 extra riders have to go someplace and in the strict mathematical sense they go to the bottom to stand in line. This point is rarely pointed out in lift manufactures marketing brochures with the exception being Riblet.
In reality, tests done at Agony Acres and other areas have proven that the riders are absorbed into the ski runs. This seems to create a higher density run that slows the skier and therefore increases his total round trip time, so there is no apparent wait in line that nathanvg predicts. Unless it's in the early morning or at the end of the ski day.
Other odd but significant factors for slope density are HSQ riders endurance throughout the day and seasonally too.
If highspeedquad says a HSQ's speed can be increased that’s true but it makes the comparison invalid because FGQ's top line speed is … well fixed.
Other arguments for either side comparison are actual loading capacity vs. marketing brochure capacity.
For more info use skilift org's search – capacity, loading, and Riblet.com.

Ryan B

[Aussierob]

Quite a good bit of maths. The only problem is your numbers are way too small. At most ski areas and particularly the large ones, the area size and number of skiers is significantly larger than the difference between the number of people on an HSQ and a FGQ.

e.g.
whistler
moderate day = 20,000 skiers
12 HSQ's say an average of 250 people on uphill side
8000 acres

12 x FGQ's would have 500 ppl on the uphill side, so 3000 less on the hill at any one time. Not a huge difference in 8000 acres (14,000 vs 17,000). Most people prefer the shorter ride time and greater amount of skiing.

note: numbers used are VERY approximate. :)

[Duck]

A fixed grip 4-place chairlift with a 6-second interval between chairs will have identical capacity to a detachable grip 4-place chairlift with a 6 second interval between chairs.

-Iain

[nathanvg]

Ryan B, on Mar 13 2005, 11:21 PM, said:

nathanvg is kinda right.
Those 100 extra riders have to go someplace and in the strict mathematical sense they go to the bottom to stand in line. This point is rarely pointed out in lift manufactures marketing brochures with the exception being Riblet.
In reality, tests done at Agony Acres and other areas have proven that the riders are absorbed into the ski runs. This seems to create a higher density run that slows the skier and therefore increases his total round trip time, so there is no apparent wait in line that nathanvg predicts. Unless it's in the early morning or at the end of the ski day.
Other odd but significant factors for slope density are HSQ riders endurance throughout the day and seasonally too.
If highspeedquad says a HSQ's speed can be increased that’s true but it makes the comparison invalid because FGQ's top line speed is … well fixed.
Other arguments for either side comparison are actual loading capacity vs. marketing brochure capacity.
For more info use skilift org's search – capacity, loading, and Riblet.com.

Ryan B
<{POST_SNAPBACK}>

You make some good points Ryan, but I don't quite understand your point on the difference in run density between the FGQ and HSQ.  Since both lifts unload the same number of skiers per a given time, it seems that they would have nearly identical density of skiers on a run.  Thanks for your thoughts.

[nathanvg]

Aussierob, on Mar 14 2005, 12:43 AM, said:

Quite a good bit of maths. The only problem is your numbers are way too small. At most ski areas and particularly the large ones, the area size and number of skiers is significantly larger than the difference between the number of people on an HSQ and a FGQ.

e.g.
whistler
moderate day = 20,000 skiers
12 HSQ's say an average of 250 people on uphill side
8000 acres

12 x FGQ's would have 500 ppl on the uphill side, so 3000 less on the hill at any one time. Not a huge difference in 8000 acres (14,000 vs 17,000). Most people prefer the shorter ride time and greater amount of skiing.

note: numbers used are VERY approximate. :)
<{POST_SNAPBACK}>

I agree that my numbers are small, but they should scale up linearly. Your numbers above seem to make the point that there are more skiers not on the lift than my numbers indicate. This may be true. Assuming that 20,000 skiers and 12 quad lifts is accurate for whistler there are many skier unaccounted for as you point out. There are several other factors that may play a significant role in your more complex example above. Some of these factors include: skiers not skiing the whole day, waiting in lifts lines and skiers taking lunch and rest breaks.

You number of 3000 skiers on all HSQ lift at a given time would indicate that only 15% of skiers or 15% of a skier's day is spent on a lift? If a HSQ lift ride time averaged 6 min. and you skied an 6 hour day (with no breaks), you would only ride 9 lifts in a day. Furthermore your average run would be 40 min long. I don't think this is accurate.

Your scenario is obviously more complex and as a result any statistics about it will have more error. I agree that as a skier a HSQ is more desirable than a FGQ. I just wanted to spark a little discussion on the issue.

[highspeedquad]

One of the things I wanted to point out was that the HSQ has the highest possible capacity, since it is easier to manipulate.

[Aussierob]

I tried to start recalculating the whole thing as the 15% number didn't seem to be right, but my brain started to hurt.

[nathanvg]

Aussierob, on Mar 15 2005, 12:01 AM, said:

I tried to start recalculating the whole thing as the 15% number didn't seem to be right, but my brain started to hurt.
<{POST_SNAPBACK}>

I rethought my number and I do think there is a slight error. The basic idea is that a skiier is on the lift 15% of the time and on a run the other 85%. Given a lift ride to be 6 min. Here is my math:

6min_____/15_______*85_______= 34 min
lift_____convert_____multiply_________run
time____to 1%______to get 85%______time

What I got before was lift time(6) + ski time(34) = 40 min

This post has been edited by nathanvg: 16 March 2005 - 04:50 PM

[ISMrider]

I think we are missing how FGQ slow down much more often for riders that are tall enough or beginners. The numbers do make sense that they have similar uphill cap. But as said before it is hard for FGQ's to reach full capacity

[skiPhreak]

With what nathanvg is saying it is also true with longer lifts can have a higher capacity because they have more chairs and take the people further up the mountain.
If u have a short lift say 500ft and it could carry 2400pph. Once a passenger reached the top it may take them about 3 min to get back down and ride the lift again. So you would have the same person riding the lift every 3 min.
With a longer lift about 4500ft it may take a person 30 min to ski down therefore the lift can serve a greater number of people because the same person would be riding the lift every 30 min. The longer lift would also have 9 times the number of chairs.
If you had a large resort with very short lifts then you would need a much greater capacity compared to a resort with long lifts.

This post has been edited by skiPhreak: 17 March 2005 - 12:42 PM

[liftmech]

I thought this was a lift site, not a math site :)

I think people are digging too deep on this one. Lift capacity really is pretty simple. Every six seconds, excepting lifts that stop a lot, two, three, four, or six people get off the lift. That won't change if the lift is 100' long or 10,000'. If a lift has a 2400 PPH capacity, then every hour under normal operating conditions 2400 people will ride the lift. It's that simple. A better measure of what most of this thread is attempting to discuss is Comfortable Carrying Capacity, or CCC. This is a measure of how many people the hill can support, based upon run acreage, skier ability, and general mountain conditions. A lift that pumps out more people than a designated area's CCC has too much capacity. One that dumps out half of the CCC coupld be upgraded. This does not take into account the wait in line; I don't know that you can really account for that anyway as lines fluctuate on a minute-by-minute basis.

[highspeedquad]

I don't think that the fact that there are more people on a FG quad as opposed to a HSQ affects capacity at all. The only thing that appears to matter is the interval.

[Aussierob]

We weren't really discussing the uphill capacity of the lift per se, rather the total number of people sitting on it at any one time, and how this affects the number of people actually skiing at any one time. A FGQ that has the same uphill capacity as a HSQ will have double the number of people on it at any one time. (assuming they are both fully loaded)

[liftmech]

True, and why rope-evacuating a FG is more time consuming than a detach. I guess looking at it that way, Rex ('88 Poma detachable) and old Midway ('88 Poma FGQ) at Crystal would be a good example. They were both around the same length, but where Rex had 87 carriers Midway had 161. Midway would have 320 people on line if it was fully loaded, where Rex would only have 172.

[SkiBachelor]

I just read in SAM that there is an 18% difference with slope congestion between a HSQ and FGQ. The HSQ having the higher slope congestion of course.

[nathanvg]

SkiBachelor, on Mar 20 2005, 01:44 AM, said:

I just read in SAM that there is an 18% difference with slope congestion between a HSQ and FGQ. The HSQ having the higher slope congestion of course.
<{POST_SNAPBACK}>

18% is an interesting statistic. I wonder what the conditions of the test that generated this stat are? The whole FGQ vs HSQ capacity question is largely dependent on the type of terrain. It is particularly evident at Midwest ski areas. This is because Midwest ski runs are typically directly under or next to the lift. The result is that the ski run is the same length as the lift but skier ski much faster than ski lifts. The result is that the number of people on a lift at a given time is the largest factor in ski area capacity. As you consider longer run length to lift length ratios the effect is reduced.

[vons]

A few years ago sam did a blurb on capacity and loading efficiency though a FQ and HSQ have the same capacities(2400) the HSQ will operate at full seed more than 95% of the time while the FQ is more like 80% therefore the HSQ would move 2280 vs 1980. The basic premise was that a lift can only operate at capacity if every guest could load and unload perfectly since in reality guest do odd things such as cartweels off the lift or step out into chairs . Due to its greater ease of loading and unloading the HSQ is able to operate closer to 100% efficiency therefor has the greater real capacity.