Advancements in 3S and MDG technology have largely eliminated the need for Funitel and BDG technologies. If you’re considering a Funitel, you might as well go with a 3S. The 3S is faster, with higher potential capacity and reasonably similar capital costs. A 3S also doesn’t incur the high energy consumption cost that’s typical of the Funitel technology.
Similarly, the BDG’s only real advantage over the MDG is a moderately higher maximum speed (27 km/hr versus 22 km/hr), without any real capacity or wind stability improvements. Not surprisingly, however, the BDG has a higher capital and O&M cost than the MDG. If you’re considering the BDG, you’re therefore likely to opt for the MDG in the end.
That leaves us with a low-end market technology (the MDG) and a high-end market technology (the 3S). But what about the middle-market?
The curious thing about markets like Burnaby Mountain and Calgary are that the environmental conditions there are such that the wind stability offered by the 3S make it the logical choice.
However when you look at the capacity, speed and cost factors in both those situations, an MDG would suffice fine. Both cities would be more than content with an MDG system were it not for the needed wind stability. In fact, wind stability is the only reason for either of these cities to actually opt for the 3S. Is that worth the extra cost?
Let’s be clear, cost is a major impediment to implementation. At a price point of 2-3 times that of an MDG, it becomes much harder for a city to justify implementing a 3S over a more standard transit technology. However, with a wind stability threshold 30% lower than a 3S, it becomes impossible for many cities to implement an MDG.
See the problem?
You may not need all the bells and whistles of a 3S, but the one bell-and-whistle you do need (wind stability) the MDG doesn’t possess. You therefore must opt for the 3S.
So here’s the challenge and opportunity for the industry: Design a technology priced somewhere between an MDG and 3S system (in both capital and O&M costs) that offers the capacity and speed of an MDG but the wind stability of a 3S.
Think of it as the Minivan of cable transit:
"Seating for eight people at the price of a family-sized sedan? No way!"
44 Comments
Why not BDG? A BDG has longer spans and uses less energy than an MDG of the same capacity. Most cargo gondolas are BDG for a good reason.
Gondolas for ski resorts have a height difference between the stations. The potential energy needed to transport people uphill is much higher than friction and rolling resistance. For urban gondolas there are much less height difference. So reducing rolling resistance and friction will become more important.
Legitimate point, but it’s a question of cost-benefit. A BDG has spans longer than an MDG of around 300 meters and the energy consumption difference is ~ 0-10%. Is that worth the higher capital costs? Is it worth the cost of having to design, build and procure land for larger towers and stations?
I’m not saying the BDG won’t be useful in certain specific applications, but generally speaking, it’s not a technology that’s commonly implemented anymore.
I’ve been skimming trought the Burnaby Mountain feasibility study: http://univercity.ca/upload/GONDOLA_FEASIBILITY_STUDY_FINAL_EMAILABLE%20042209.pdf and they don’t seem to agree with you on the maximum span. They list tower spacing as 100 to 300 m for monocable and 1500 m for bicable. So the difference seems to be more than 300 m, or am i misunderstanding something?
They also say that the maximum wind speed for monocable is 60 km/h and 80 km/h for 2s, so there certainly seems to be a difference. Is that difference significant enough, is ofcourse a different matter.
Interestingly enough the wind factor is mentioned as major reason to choose 3s before 2s or monocable, but they then justify it with this:
“over a five-year period from 1973 to 1978, a total of 19 hours (3.5 hours/year) averaged wind speeds greater than 60 km/h with zero hours averaging
wind speed over 80 km/h. Additional data from Environment Canada indicates that over an 11-year period from 1978 to 1989, 46 hours (4.2 hours/year) had a wind speed of over 60 km/h in a two-minute period at the end of the hour, while zero hours showed wind speeds over 80 km/h”.
So if zero hours showed wind speeds over 80 km/h, shouldn’t BGD actualy suffice?
Here’s the problem: Like all transport technologies, statistics are relative to the context they’re implemented in. A monocable gondola in an inclined alignment needs fewer towers than a gondola laid out flat. Now take a situation where you have an alignment with both.
Furthermore, there appears to be little consensus within the industry about what a BDG can and cannot do. Three years ago MDGs could handle 50 km/hr winds; 1 year ago its 60 km/hr. Now I’m hearing 70 km/hr. Meanwhile, in those last three years, the BDG has virtually disappeared from company catalogues. Why? I’m not really sure.
There’s always the possibility that the 3S and MDG carry with them a higher profit margin than the BDG and as such the industry has been pushing people away from BDG technology. Note, however, that that’s just pure and blatant speculation on my part and I have no proof or data backing up that theory.
I’d prefer BDG because of the extra rope/cable. I have a feeling it is safer and better in maintenance.
I really think the MDG/BDG technology and design still isn’t pushed to its maximum. 3S is well and good, but it really is a big gun, like you said.
Coming up with a clever design for the MDGs, with a little more space, but probably same capacity would be interesting imho – probably even more than a new technology between MDG and 3S.
Whatever we call it, I think we’re saying the same thing.
Station size depends on capacity and speed not on technology. See Koblenz with its small sized 3S station. Tower size also depends on height and span of the cable for same spans MDG and BGD Towers will be almost of equal size. Safety and evacuation options also better for BGG and 3S. Regulation migth rule out MGD in some cities. The ride is smoother if having a supporting cable.
A BDG is able to run on a rail instead of a cable. So curves would be much easier than on a MDG. This would open many routes not possible with MGD
In my opinion a gondola specifically developed for urban needs will be a BGD (3S is a variant of the BGD principle) There is still some homework to do for a real urban gondola.
Actually the electro-mechanical components in a BDG is larger than in an MDG configuration. The Koblenz system minimized these factors through a fairly creative design, but with a heftier price point.
I think we’re both saying the same thing: There needs to be a “middle” technology.
Which components are larger? The motor,bull wheel and pulling rope have same size or even smaller than on a MDG. An counterweight or a hydraulic tensioning for the supporting cable is needed and might be the cause for the extra cost and some size.
There are only two options
A: the pulling cable is also the supporting cable (MDG,Funitel)
B: There are pulling cables and supporting cables or rails (BCD,3S, Funicular,Cable Metros).
True, everything can be smaller. It needs to carry the same load, but at the same time the motor on a BDG doesn’t have to take care of the load, just the pulling – so the bull wheel can be smaller. Only thing maybe: the foundation needs to be a bit bigger, because those two cables probably do weight a bit more than the mono one.
And the separation is indeed an advantage, when it comes to the station-railing and corners.
(I honestly think BDG has positive effects on the wind stability – but I right now I can’t find the article I read it in. Will let you know)
I used to believe the same thing (re: wind stability) but my industry sources are telling me that’s no longer the case.
station size would be dependent on technology when you look at how the vehicles are accelerating from crawl to operational speed. you can’t just shorten the station and have people blasted up to full speed.
since max speed of a MDG is less than a 3S it makes sense that the MDG stations would be smaller.
i think this is what koblenz somehow got around
Well then (BDG): no wind stability, but longer spans, bigger cabins and faster speed.
If wind stability is really the issue I don’t get it, why they are still on the mountains – and running. Still don’t get it, why they don’t change the cabin design towards a more aerodynamical one (see Leitner cabins for instance http://www.fendels.info/scms/media.php/12445/Seilbahn.jpg – there was a better photo of white cabins within a station, but couldn’t find it when I was looking for it).
Besides changing the design: put the gravity center a bit deeper (by putting/moving weight into the cabin ground or simply increase the length of the suspesion gear/hanger), so it’s more stable on the line. You could even put a pendulum in the cabin ground (like skyscrapers have as an oscillation damper)
But if roads are rough, cars shake too. Same for trains and even for planes!
I think the issue, LX, is that when you’re dealing with mountains, you’re dealing with (largely) recreational uses. If the gondola goes down for 7-10 days per year because of heavy winds, no issues. That can’t happen in a PT situation.
Especially in (for example) situations like Burnaby Mountain. One of the explicit reasons for building this system is to prevent the 10-14 days per school year that the bus route up the mountain is shut due to inclement weather.
Hence the reason for the upgrade to the 3S.d.
So we need to find out at which explicit situations the different CPT’s on this planet weren’t running.
And also need to find out what were the particular factors for shuting down bus route due to inclement weather (i.e. icy roads, snowy roads, hurricane, heavy winds, missing ability to see the road because of snow/fog whatever or personal failure because forms of transportation were not prepared properly).
#LX
“If wind stability is really the issue I don’t get it, why they are still on the mountains – and running.”
No, if the wind on a mountain is > 60 km/h, these ropeways are stopped or the gondolas will be driven into the garage.
Because of cross-wind, gondolas can swing with the fixed cable and this twisted driving cable turns out of the rope pulleys.
Skiing at a cold wind speed > 60 km/h isn’t funny, so it is not a problem.
Some Tricable systems were built to transport passengers down from a glacier to the valley in any case whether the wind is too strong. They are driving up to 100 km/h (cross-)wind.
But at gondola transit you cannot say”Today we don’t ride, wind is too strong, go by foot!”.
Good to know.
60 km/h are for MDG and BDG I guess.
Q: I wonder what 60 km/h wind means on country side?
A: 60 km/h equals on the Beauforts scale around number 7/near 8. Storm means 10 or bigger and I’m not sure if all transit still runs at that number, but 12 means hurricane-strength and they surely stop running at that speed.
Q: So what is the Bft-number a 3S system could run?
A: “High Wind Stability: Designed to operate in winds up to 80km/hour, cabins ride on two cables, making the PEAK 2 PEAK Gondola the most wind tolerant lift on Whistler Blackcomb. Testing at other Doppelmayr 3S installations have measured sustained winds at 100km/hour with no decrease in performance.”
Source: http://ww1.whistlerblackcomb.com/media/gondola/safety.asp
So a wind map will tell if and which CPT-form is possible at that specific location.
Why couldn’t a monocable be designed for wind stability cables instead of support cables. IE a 3S looking system where the two support cables are not support cables but only really apply force when wind is involved.
Instead of 2 cables on each side for wind stability, how about a cable at the bottom to hold the bottom of the gondola steady? Might even help keep the gondola steady during acceleration or deceleration.
Dibs on the patent for this! 🙂
That’s what we should do, we should create a collective of gondola enthusiasts, solve the problems and then just file every patent we can think of :).
That’s what I’m talking about.
Have cables under the cabin that work to keep the cabin steady horizontally instead of holding it up.
Like a car suspension system but turned 90 degrees and recieving shocks from the sides.
If you needed more wind resistance the bottom cables could be tied to the ground between towers with wires similar to how radio masts resist wind movement (or how tents tie down to the ground). This adds to the eye sore factor and impacts the ground space required but not to a huge degree.
I suppose you could even just go for 2 cables. One on top for support, one on the bottom for both wind stability and motive power.
(sorry if this is what [Sam] meant – I assumed he was still talking about 3 cables)
I’d pretend to understand what you just said, but I don’t. 🙂 Do any of the engineers around here know what Seth’s saying?
Me neither.
But maybe I do.
Like using a BDG. It is working like a MDG, but the second cable is not for loading, it’s for stabilisation.
why not put MDG sized cabins on a Funitel configuration? they both have detachable grips. then, technically you would end up with a single-cable system that has faster operational speeds and increased wind stability as compared to a MDG since each cabin is supported/propelled by “two” cables. plus instead of two giant vehicles running back and forth you get lots of smaller vehicles running more frequently.
Isn’t part of the reason for the increased wind stability of a 3S that the cabins are larger and heavier? Obviously a Funitel has the widely-separated cables and short hangers for even more stability. Some newer MDG and chairlift installations in particularly wind-prone parts of ski areas use carriers intentionally designed to be heavier, so they don’t swing as much.
Was once on a lift, right before they closed it, where the operator at the top had to stop it before we reached each tower (we were the last loaded chair) and wait for a lull in the wind before creeping us past it. That wasn’t any fun at all.
Yes and no.
Larger means a larger surface for wind to “press” against. Again the weight and the distance between the two ropes of one meter is helpful against wind.
Funitel technology isn’t as flexible and small as 3S is (especially in corners/station)
But using MDG with a safety-and-stability-cable would be a nice idea. We should put some thoughts into it.
so, why not decrease surface area … if we design it like a cage the wind will blow right through
Larger gondolas have less surface per weight than smaller ones. Thats the Square-cube law. So for wind stability a few large gondolas are the best solution, while many smaller gondolas have a better wheigth distribution and thus a lower cost. If wind stability is a top priority we also should consider Aerial tramways. The need small station have a high speed and decent capacity. And nothing beats a Funifour when it getting windy.
# “Have cables under the cabin that work to keep the cabin steady horizontally instead of holding it up.
Action point of the traction force should be near the carrying rope, or you get a parallelogramm linkage. Think of a children swing you are pulling.
And the swing of a gondola by cross-wind could be in the direction of the cable too, a cable under the cabin doesn’t prevent swinging to this direction.
“Action point of the traction force should be near the carrying rope, or you get a parallelogramm linkage.”
One advantage of gondolas is, they are always hanging in a vertical position whether the angle of the carrying rope is 5 or 45 degrees. If you have the traction cable fixed at the bottom, this system doesn’t function.
Good points but couldn’t the cabin ride on pendulum-like struts that can flex and pivot but even out wind shocks and resistent horizontal swing movement. Think monster truck suspension.
Wind in the direction of the cable would be up-drafts wouldn’t it? It would seem that having suspension on more cables would resistent such movement.
You cannot apply for a patent, if an idea was published (here) before !
§:o))
Perhaps we could save money with a ropeway its wheels are riding on the returning traction rope, you understand? (these ropeways still exists).
But with two traction ropes = two track ropes to improve wind stability.
( A problem is, the traction rope at intermediate towers is supported by wheels and these wheels must be driven over by the wheels of the gondola.)
If the distance between two stations in an urban area is not so far away, you don’t need so thick track ropes or support towers, so the traction ropes can be enough.
But this system has some disadvantages of a funitel (many wheels on the route, if it is possible with towers)
With this system only one ropeway exists as public transport:
(from Camorino to Alpe Croveggia, Switzerland)
http://www.stahlseil.ch/gallery/main.php?g2_itemId=73538
(there it is not a problem to drive over the support-wheels by the wheels of the gondola, the support-wheels are wide, the driving-wheels are thin)
Neat system! Thanks for the photos. Just to clarify, I wasn’t suggesting the bottom cable be a drive or support cable. The sole purpose of a bottom cable would be to provide wind stability so hopefully it’s much cheaper than a BDG system. With both the top and bottom secured, there should be much greater wind stability than even BDG systems.
Much technical invention is required for detachable grip systems with a top and bottom cable. Not sure how both top and bottom can be detached.
And yes, anything we discuss here is by definition public and not patentable! 🙁
At a BDG you have one track rope,
at a 3S you have two track ropes,
at a BDG with a rope at the bottom you habe a 3S too.
What ist the advantage or why it is cheaper?!?
This bottom rope needs a tension. If it is fixed on ground how drives the gondola-wheels on this rope? On the top side? So you need a thick track rope = 3 S.
This only one existing ropeway has only one gondola to take some residents of a hill farm down to the valley, I believe.
If you give more than one gondola on it, the traction = track rope must be thicker and so you have the disadvantages of the existing funitels (it needs very much energy to move the ropesm or to turn round the ropes and the ropes must more often replaced/exchanged than at a 3S.
The only reason a bottom rope might be cheaper is that the sole function of the bottom rope is wind stability. In a BDG system, the support rope must be heavy for support reasons and the haul rope must be heavy to haul the gondolas. A wind stability rope at the bottom could potentially be much lighter.
(Yes there are other complexities that I’m ignoring in the above assertion.)
Of course, that system has but one carrier, and the design of the grip and rollers means it can’t have support towers.
The problem with this scheme in general is that it adds nearly as much complexity as a Funitel or 3S design. If the bottom cable moves with the haul rope, that’s another set of grips for each carrier, and another set of sheaves on each tower, and each station needs another bullwheel and another set of drive rollers and attach/detach rails, plus all the fault-detection circuitry. If the bottom cable is fixed, each carrier needs a set of sheave trains, which need to be on both sides of the cable as well as the bottom, greatly complicating the design of the bottom cable’s tower supports. And, in both cases, the tension system needs to be set up so that the top and bottom cables are more or less the same distance apart at all times despite varying load factors, thermal expansion, etc.
Now, I could see the merits of a Funitel with 8 to 16-seat carriers like an MDG. It would allow for smaller stations and towers, and probably be less visually obtrusive in general. I don’t know if there would be major cost savings, however.
I spent some tie to red teh websites and attached catalogues of
http://www.doppelmayr.com/en/doppelmayr-international/products/bicable-and-tricable-ropeways.html?country=all
and
http://en.leitner-lifts.com/Produkte/2S-und-3S-Bahnen
Doppelmayr states:
Bicable ropeways or “BGDs” (Bicable
Gondola Detachable) combine the benefits
of a detachable gondola with those
of a classic reversible aerial tramway.
The 2S system has one fixed, fully locked
track rope on which the carrier travels
and a circulating haul rope which is
clamped to the carriages. The 2S system
is a detachable circulating system for
cabins carrying up to 16 passengers
each and a total transport capacity of up
to 3500 PPH.
These ropeways are characterized by
very high wind stability, low energy consumption
and the capability to cope with
very long rope spans. Infinitely adjustable
travel speeds of up to 7.5 m/s are
possible.
In the German text they write explicit: Das
Tragseil ermöglicht die Realisierung von
langen Spannfeldern zwischen den Stützen
und die besonders gute Windstabilität
unterscheidet die 2S Bahn von einer
klassischen Einseilumlaufbahn.
Means a BGD has a better wind stability than a BGD
Leitner:
Rising to the challenge. The use of separate track and haul ropes permits lines to be designed with extremely long spans of 2,500 m and more for effortless negotiation of steep and rocky slopes with impressive vertical heights. Therefore the environment does not suffer – thanks to a minimized number of towers requirement for a reduced footprint. Even with its long spans, the bi- and tricable gondola performs extremely well in windy conditions. Such details as rope saddles with a large angle of wrap, deep sheave grooves, side plates and rope guides all combine to eliminate the risk of deropement even at wind speeds of over 100 km/h.
With both Manufacturers the Gondolas of a TGD are about the double capacity of a BGD while a large BGD can reach same capacity of a BGD. Clearly an MGD has lower investment cost and is good enough for most ski resorts. Meaning for investing in BGD you get longer spans and better wind stability for higher cost but only a very small capacity and speed increase.
Rough costs per kilometer for different gondolas in million € / pph
MGD : 3,5-6 / 2000-2500
BGD : 5 -7 / 2500-3500
3S :10-12 / 2500-3500
there’s very much work to be made regarding gondolas and ropeway, its an estabished, well proven and very safe techonology, but last innovations dates from early seventies