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Ski Lift Capacity Detachable Vs Fixed Grip

Detachable (high speed) chair lifts usually do not have a higher capacity than their fixed grip counterparts (aka... there aren't any more people on the hill).  The difference in speed is compensated for by wider chair spacing.  Detachable lifts must have a wider chair spacing so that the chairs do not bunch up in the terminals during loading while the chairs are moving slowly.

The industry standard capacity for a quad is 2400pph (people per hour), regardless of whether it is detachable or fixed grip.  The length of ride is different, but the number of people being put on the mountain is exactly the same.  Detachable quads do allow for a higher capacity under special conditions, but it is rare to see a detach with a capacity higher than 2400pph.

It's all one big mathematical equation, in reality.  Consider the following:



C= capacity in pph (people per hour)
P = passengers per carrier
T = loading interval in seconds (time between each chair passing the load board)
R = rope speed in fpm (feet per minute)
S = carrier spacing in feet

C = (60 * P * R) / S
T = (60 * S) / R    ---or---    T = 3600 / (C / P)

Let's look at a hypothetical situation.  Lift "A" is a fixed grip quad running at the maximum legal speed of 400fpm.  Lift "B" is a detachable quad with a maximum design speed of 1200fpm.  Both lifts have an industry-standard comfortable loading interval of 6 seconds.

Lift "A"

First, we need to determine the chair spacing based on T = (60 * S) / R

6sec = (60 * S) / 400fpm
2400 = 60 * S
S = 40ft

Now, we can plug in our chair spacing to determine our capacity based on C = (60 * P * R) / S

C = (60sec * 4people * 400fpm) / 40ft
C = 2400pph

Lift "B"

We'll start by calculating chair spacing as we did with Lift "A"

6sec = (60 * S) / 1200fpm
7200 = 60 * S
S = 120ft

Again, we move on to capactity

C = (60sec * 4people * 1200fpm) / 120ft
C = 2400pph

That's theoretical, or, design capacity.  Actual capacity is a whole 'nuther ballgame (based on loading efficiency, stops, slows, percentage of load, etc.).

Comments (1)

You sound like you might just be able to answer my real question...which is " What resort(s) actually lift the most people the greatest distance". I am thinking that the lift capacity numbers we currently see posted, and are often used to compare resorts, are really flawed in that they don't consider the distance that people are lifted. For example..one resort might have a published lift capacity of 10,000 skiers per hour, but only be lifting them 1000 ft and another might have the same lift capacity of 10,000 skier per hour but be lifting them 4000 ft. Don't we need to be looking at a different ratings number that reflects how many feet these 10,000 skiers are being lifted???
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