Doppelmayr has published its 2012 'Worldbook' showing all the lift installations undertaken in the past year: [media.doppelmayr.com]

Interesting that they are still cranking out drag lifts.

Mike in Edinburgh
Assorted scottish pics - www.prog99.com

How much for a 6 seater detachable chairlift from Ciste Carpark to Ptarmigan?

According to that PDF they have installations in North Korea. Hum just went down many notches in my estimation.

Not surprised that surface lifts are still being cranked out, in many places where a lift is required a chair or gondala is impractical. I did note that one of the drag lifts they put in had high resolution CCTV along the entire length that could be monitored from the bottom.

As to a 6 seater detachable chairlift from Ciste Carpark to Ptarmigan, been over this many times but detachable chairlifts don't appreciably increase the capacity of the lifts (the limit is the loading interval) but cost much more to operate in both power and maintenance costs. From a practical perspective they are unlikely to make economic sense in Scotland; even if the increased capital cost of acquisition could be met through a subsidy or grant, the increased long term running costs would place an unsustainable economic burden on the centre operating it.

There are operator advantages in detachables, particularly on exposed lift lines - which need to be considered against the running costs balance.

Just one example is clearing carriers of snow after an overnight fall. For a given lift line a detach will have at most half as many carriers than if it were a fixed grip. One person can clear all the chairs of snow on Kirkwood's Cornice Express in around 12minutes with the chair at full line-speed. By contrast it takes at least 2 people close to an hour to clear every chair on the Wagon Wheel fixed triple, as it has to run at 50% of speed to be practical and the carriers are too close for one person to manage the task.

Of course if the chairs are off the line and stored inside (as was the case with the former Carpark and White Lady Chairlifts) you avoid that issue and the potential for storm damage to the carriers entirely.

As on modern chairs cross wind tolerance is banded to % of linespeed, a high speed quad running at 50% line speed is still going at a speed which is pretty fast for a fixed grip quad, but the high speed detacah would thus have a higher wind tolerance. This is also helped by high speed lifts having fewer heavier carriers and using RPDs (Rope Position Detectors) which can slow lifts before rope movements cause a derailment against the traditional break-forks used on fixed grip lifts.

In financial terms you also need to consider the impact of the lift on attracting customers. For CairnGorm replacing the White Lady Tow the costs would rise considerably between new T-bar, fixed grip quad and a high speed sixpack, but so would the operational reliability and the power of the new lift draw people to the mountain. Dopplemayr's study of the ski area in 2001 stated that a modern 6 person detach lift would be closed due to wind on fewer days a season than the Ciste T-bar.



Edited 1 times. Last edit at 10.42hrs Wed 15 May 13 by alan.

I also have a notion of a hybrid chairlift. Basically the chairs can be taken on/off the line and spacing adjusted just as they are all "detachable" but in normal operation it runs as fixed grip. The concept is by only having one station that can take the chairs on/off the line you have lowered the capital costs, but by being able to quickly take chairs on/off the line in response to weather conditions you gain the benefits of a detachable chair for running costs without the power budget costs.

As far as I can determine the power requirements for detachable chair lifts are much greater than for fixed grip and this is the killer for running costs. Also for example there is no reason why a fixed grip chair could not have rope position detectors to enable it to operate in more adverse weather conditions.

I don't believe such a chair exists but it is my view that it would be the ideal compromise for Scotland between a fixed grip and a detachable chairlift. The biggest gain is the ability to take the chairs off the line and store inside to protect against weather related issues.

As for high wind operations, I would love to see a graph of lift usage against wind speed. It would require the introduction of hands free passes to collect the data, but my hunch is that before even a fixed grip chair is at it's limit most of the punters have gone home, and with my hybrid concept you could easily reduce the number of carriers on the line to keep it running at higher wind speeds.

Another advantage of my hybrid concept would be on the access chair at Glencoe. Lots of chairs in the morning and end of day to get punters on/off the mountain, but during the day take some of the chairs off the line to reduce running costs. Would also work on less busy days as you could tailor the number of chairs on the line to ticket sales.

"Cabrio" lift for Cairngorm any-one ?

.. with 2 detaching intermediary stations, bottom of aonach bowl and top of WW.

I'm not convinced about this Hi speed detachables use more power than fixed grip argument.

For the same uplift capacity, a fixed grip (because it runs slower) needs many more carriers and passenger on the line than a detachable express. The load being hauled at any one time is therefore greater than a detachable, therefore requiring more energy to balance the extra power input to run at higher speed of a detachable.

Assuming one takes advantage of the higher speed of a detachable, top stations need to detach chairs prior to unloading, or its carnage as the passengers get flung off, and the chair whips around the top bull sheave. When it's quiet, as with a gondola) you just reduce the line speed to lower power requirement (which you can't really do on a fixed grip without the users complaining).

The other consideration with big (ie 6 plus seaters) is uplift capacity. The Bochasses lift in thge Yearbook has replaced 3 T bars and still added additional capacity to the area they served. That is a significant reduction in operating costs, particularly wages.

How much are we talking about? €2 million?

Arm chair physicists...

There are a number of flaws in that reasoning. Firstly a chairlift is a semi balanced system. If we consider a fixed grip chairlift that has no passengers the energy required to lift a chair from the bottom to top station is recovered as it comes back down. The losses are rolling resistance on bull wheels, sheaves etc. and air resistance. There is also the energy required to overcome the inertia of the system when starting it up.

However a detachable chairlift also has decelerate and then accelerate every chair as it goes through the top and bottom station. This is a huge energy expenditure and as far as I can tell no detachable chairlift has a kinetic energy recovery system aka KERS to offset this cost.

With passengers added into the mix all chairlifts have to expend energy to accelerate the passengers to the line speed. This is dependant on the square of the velocity of the line speed of the chair. So a typical detachable chair operating at 6m/s compared to a fixed grip at 3m/s requires four times the energy to accelerate the passengers to the line speed.

We also have the fact the power required to overcome aerodynamic drag is related to the cube of the velocity. So with the above example line speeds that is nine times the energy to overcome aerodynamic drag. Now admittedly you will be exerting it over a shorter period of time, but it still adds up to more energy required to operate a high speed detachable than a fixed grip.

Note the number of passengers on the line at any one time is a red herring. What you need to look at is the energy required per passenger. As I have pointed out previously the limit on the number of passengers per hour for a chairlift is dependant not on the line speed of the chair, but the loading interval. This changes very little if at all between a fixed grip and detachable chair. You do get slightly more on a detachable due to end effects but it is negligible over the day.

Roughly you need four times the energy to accelerate each passenger, a bunch of energy to accelerate each chair twice, four and half times the energy to overcome aerodynamic drag and more to overcome "rolling" losses in the system. Consequently the energy required to run a detachable chairlift is much higher than that of a fixed grip.



Sure read my notions of doing similar things at Glenshee on Sunnyside. However this is separate from the fixed grip/detachable argument.

Can't say that I've seen many 3600 p/h uplift fixed grips, but there are numerous 6 and 8 seater detachables.

And lots of detailed theoretical discussion there, but can you reference an actual worked example ?

Alan, was the doppelmayr study of cairngorm ever released or made public?

I raised the same point a short time ago ?

Has any experienced elevation transfer operators every posted here on this subject