Authorities in South Korea say a rollback at the Bears Town ski resort involved approximately 100 people. The mountain’s base-to-summit detachable quad went backward at approximately 3:00 pm today and at least 20 chairs stacked together in the bottom terminal. Some riders jumped or fell from the lift while others were pinned in the station. At one point, video of the incident shows guests grabbing on to chairs in an attempt to stop the lift. Police say numerous skiers jumped or fell while firefighters rope evacuated others after the ropeway stopped. At least one child was taken to the hospital.
Rollbacks of modern lifts are exceedingly rare and a detachable lift rollback is even more unusual. The quad where the incident occurred is called Challenge and appears to have been built by Poma some time around the early 1990s.
Bears Town opened in 1985 and is situated just 45 minutes from the South Korean capital of Seoul. “Our sincere apologies to the customers and their families who were affected by this accident,” the resort said in a statement. “Bears Town plans to immediately suspend all lift operations in the ski resort in addition to the lift that caused an accident, and to begin an immediate safety inspection,” the statement continued. “We will actively cooperate with the fire authorities and related agencies and take measures to prevent reoccurrence. Currently all employees in Bears Town are focused on rescue work and customer communication with the victims as a priority.”
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Bears Town ski resort appears to be located just North of Seoul. https://www.google.com/maps/search/ski+resort+near+Bears+Town,+Pocheon-si/@37.7106993,127.0195293,10.34z
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Lift running on evacuation diesel motor possibly with all brakes manually bypassed?
One hit of Emergency stop will cut the engine and with all brakes pumped open, lift will roll back. Detachables don’t have a mechanical roll back dog as reverse operation is in their design.
Footnote : The guy in the yellow who jumped and spun 180 degrees to ski away is a freakin legend!
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This is a Poma lift. It does not have reverse operations . And does have a High Speed roll back in the gearbox.
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Agree, the Poma’s of that vintage (late eighties??) did not have a reverse run capability, at least here in US.
That looks like maybe a TB-40 or 41 grip from the video.
Took Poma a long time to get reverse run in the system. Doppelmayr had reverse operation at least since the mid 1990’s..
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So, gearbox rollback has failed?
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SC is correct and all the Detach that I worked on
( over 50 ) that had a Lohmann gear box have a mechanical roll back protection that has to be manually pull out and ni-passed to run backwards?
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I had no idea a detachable rollback was even possible, let alone capable of being that catastrophic
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It’s certainly possible. There’s nothing different on a detach from a fixed-grip, as far as the machinery that drives the rope. That said, there had to have been at least a couple of safeties bypassed for that to happen. As others have noted, this vintage of Poma has a high-speed rollback device inside the gearbox that must be mechanically disabled to even start going backwards.
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Two reasons a Detachable lift rollback is relatively slow motion compared to a fixed grip lift.
Terminal Friction & Unit weight
1. Terminal friction can be as high as 25%, that’s energy needed to turn all the accelerators, decelerators and turn-a-round
2. Even though the Detachable lifts are high capacity, the line unit weight is typically less than a fixed grip.
Unit weight Example: a 2400 pph fixed Quad at a 6 second interval could have a carrier every 40′ at 400 fpm.
A 2400 pph Detachable Quad at a 6 second interval could have a carrier every 100′ at a 1000 fpm.
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In my experience the rate at which a detachable accelerates in reverse during a roll back event is entirely due to the profile and not much else. Despite the friction in the stations, a constant rising profile with no flat sections or combination assemblies will take off backwards extremely rapidly. eg 7th heaven at Blackcomb.
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What happened with 7th heaven at Blackcomb?
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He’s using it as an example of a certain profile, not an actual accident (unless there’s something I missed).
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This was observations made at load test. The RB brake has a six second delay to close from activation. The lift gets moving pretty quickly.
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Still saying same profile, same capacity fixed grip vs detachable. Fixed grip with a carrier every 40′ to 50′ and a detachable with a carrier every 80′ to 100′ The fixed grip will win the rollback race.
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A fixed grip will be quicker, but a detach is not slow either. Profile is king for either type.
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I’m not the most familiar with poma but it appears to be older than 1990 more around 1985 BUT I’m no expert. Kind of interesting though to see a high speed lift go into rollback and knowing that it is going to be a mess to fix or in this case better off for them to replace it. Here’s a photo I was able to find of the bottom of this lift at least I believe. https://lh5.googleusercontent.com/p/AF1QipPrFf8hCnPXrCLWmdJA_EphBPWSo9Flol3Mr0Cw=w2560-h1440-pd
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I’d say 1987-1988, the bottom terminal looks nearly identical to Big Burn at Snowmass.
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The terminal seems to be a European Omega design, which debuted in 1990 or 1991 with tire contours instead of chain-drive ones. This design only subtly influenced North American designs throughout the 1990s, whereas earlier terminals used in North America (such as in Big Burn) were the same as those used worldwide.
Here’s a pretty good example from France: https://www.remontees-mecaniques.net/bdd/reportage-tsd4-des-gondrans-poma-2234.html
Most of the Omega designs Poma built were very compact, so much so that they could use one mast instead of two – but that limited them to 4.5 m/s (900 fpm) max speed. This lift has 2 legs and a max speed of 5 m/s (1000 fpm) but it is of the same design, so I’d probably place it around early 90s.
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I believe this is the lift that rolled back at bears town.
https://www.remontees-mecaniques.net/bdd/reportage-tsd4-challenge-poma-6036.html
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Can newer Leitner poma chairlifts run in reverse?
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Yes
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Interesting, I thought that was just a doppelmayr thing. I find it interesting that the chairs started piling up in the terminal, since the early pomas weren’t designed to run in reverse, maybe the grips were not detaching as they entered the terminal.
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Grips should open in reverse, that is a mechanical opening/closing rail.
If the spacing clutch’s were on that end they may have been in the disengaged position and carriers could start stacking there?? Hard so see where the stacking started in the picture I saw.
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I have to think there was a similar scene going on at the top (me being kinda reminded of the destruction that happened during the rollback tests on the Eskimo double).
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I agree with Kirk. Grip rails are stationary, so they should work the same in reverse. My guess is that the chairs are stacking up, because the chain/tires are only designed to go one direction, so they are probably stopped.
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Poma grips don’t generally go backwards due to the profile of the closing rail. As the chair travels out, the slope of the rail is gradual to open the grip. Once the grip is on the rope, the profile is steep to get the grip closed quickly. The poma grips won’t go backwards through this steep profile as the the rail acts directly on top of the spring resulting in very high forces. In this case it seems the carriers have been forced through.
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Kinda cool to see all the mechanics here discussing this so quickly. im almost 20 year lift tech myself. wonder if brakes were just not adjusted properly and it got a little heavy. not sure that anyone is goverened like we are here in the states. when i worked in NZ it was not regulated nearly as closely it seemed
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Found this on youtube
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2018 Georgia rollback 2: electric boogaloo
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We’ve only heard of a few (2-3?) rollbacks in the past few years but they do happen occasionally. I am grateful that there are places people can come to discuss these scary and often tragic situations. There are always going to be curious people out there, myself included, who can speculate with what little knowledge they have (speculation is ok, but getting the facts is more important) But I think for those die hard lift mechs and techs, they will absorb every bit of information they can.
In this situation, you may think.. “All I can do is press stop, or emergency, and pray” but one might also ask “what else can I do? Is there something I can do if I rush up into the motor room?” or “what will I do to help those individuals on the chairs?”
Keep talking about it, folks.
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Agreed, it’s definitely an interesting and useful forum!
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Turning off the control power is your last best hope.
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When I was working for Doppel I was sent to Austria for training While there I was sent to work on a new Installation that was getting ready for load test
At the return terminal there were a fair number of 40 litres plastic cans filled with a very heavy material
When I asked the Doppel engineer that I was working with why these cans were at the top his answer was that when all the redundancy failed the last resort was to allow the lift to roll backwards so as to unload the passengers There was a hydraulic set up in the middle of the terminal so that the lift mechanic could visually watch and control the roll back speed
The heavy plastic cans were used to keep the installation rolling backwards
During the load test, which took about 5 days, they manually pump the brakes open and allow the installation to roll backwards!!!
I was the only guy there that was freaking out!!!
Not able to speak Germane, I was never able to find out at what point did they apply the brakes
They also allowed the lift to roll backwards when all the gondolas were empty until it came to a stop on its own
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Poma detachables of this vintage have no feature to operate in reverse. If the lift is going in reverse, such as in this situation, it would be very bad.
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Does anyone have an update on this incident and what the cause ended up being?
Thanks In Advance
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