I learnt a lot more than I ever wanted to know about every aspect of elevators from Elevator Hacking: From the Pit to the Penthouse with Deviant Ollam (who seems to be like a professional elevator pen tester) & Howard Payne, from DEFCON 22. Highly recommended. You'll be talking elevatorese like a pro after you watch that.
That key one is crazy. (i.e. a lot of 'security' using keys seems to be nonexistent) Surely there must be less crime and criminals around than one is led to believe, a lot less, or this system wouldn't last a day, let alone decades.
This reminds me of an undergrad assignment I had when taking real time C programming. We were each given a programmable lift controller that looked very lego-ish. We were meant to write a multi threaded C program to react in real time to button presses etc to control the lift. I finished and tested every scenario i could think of - it worked great. Was feeling pretty proud of myself.
The professor gets to my table, presses a few buttons and everything works fine. He nods to himself. Then he starts yanking wires out and the lift kept going. He looks at me, shakes his head and says “safety”. I forgot to make the lift stop if anything unexpected happened :)
Thank goodness there was a safety system on this lift, even if it had to fall 84 floors for it to kick in.
This is were time-triggered architectures [1] can kick in! You divide your program into tasks and messages passed between tasks, and can then assign each task to a separate processor with a precise execution time. Same goes for messages.
They were really lucky. If they were 12 floors lower then it would have ended horribly. I wonder why didn't the emergency brakes work immediately. Shouldn't it clamp down as soon as any elevator cable snaps?
It's also very possible they were falling slowly because the brakes kicked in. As far as I know having the lift slowly hit the buffer at the bottom shouldn't be a problem other than having to reset the buffer.
This happened to me as a kid in Eastern Europe about 30 years ago. I was with my parents and my sister, going from a high story to the ground level. We were pretty much at the ground level when the cable broke. There was a sudden jolt, I don't know if it was the brakes engaging, or the cabin hitting the buffer. Then a bit of silence, and after about one or two seconds the cable came crashing on the top of the cabin. I guess the cabin was quite sturdy, that nothing happened. My Dad just opened the doors (they were and still are mechanical, rather than the motorized gliding doors you see in the US), and we left. None of us was harmed in any way.
For future reference: do not try to escape from a malfunctioning elevator by yourself. The controller won't be locked out and the elevator can start moving without any notice. Use the emergency phone or button in the elevator and wait for a technician or the fire brigade to rescueue you.
Most likely the jolt was simply the rest of the cables catching the load of the cabin. If the brakes got engaged or the elevator ran into the buffer the elevator will not be aligned with the ground floor.
Glad to hear you got off with nothing more than a slight fright though.
> For future reference: do not try to escape from a malfunctioning elevator by yourself. The controller won't be locked out and the elevator can start moving without any notice. Use the emergency phone or button in the elevator and wait for a technician or the fire brigade to rescueue you.
I think this is very good advice for the US and western countries, where you can expect some technician/fire brigade to come and help. In the communist Eastern Europe of 3 decades ago, there were daily blackouts, and probably every single days a few hundred people got stuck in elevators because of the sudden loss of electricity. We all knew how to deal with the situation, it was part of life. A cable breaking was definitely unusual though. I never heard of it happening to anyone else.
You're wrong. Sorry, but The advice is not good anywhere. Any good system will be designed for flight or flight because, despite all else, humans are humans and this was not a situation anyone is trained to handle. Anyone.
A lift that is stuck misaligned with the floor is by definition in an error state. It's something that should never happen. Lift programmers are -- much like ordinary programmers -- not omniscient. The chance of an elevator running into a bug in the software during normal operation is basically zero. The chance of running into a bug in an error state is much much higher.
If you're lucky the lift will have detected something wrong and gone into lockdown itself. If you're unlucky it'll start moving with your body halfway through the doorway. It's not incredibly likely to go wrong but the price when it does is too high to risk it.
Surely if it hit the bottom and the cable fell on them it wouldn’t be able to go anywhere? Not sure that I could diagnose that from within the lifts I use though.
You have to keep in mind that elevators have multiple cables. All you know is something, maybe a cable, maybe multiple cables, hit the top of the elevator. You don't know how many cables may remain.
That's a pretty misleading headline. It wasn't a free-fall, and it doesn't sound like the passengers were even injured when it came to a stop.
From the article: The malfunction had been caused by a snapped “hoist rope,” or elevator cable, Maloney said. Other cables were still attached, keeping the elevator from plummeting to the floor.
There are indeed a whole bunch of security features which prevent a lift from free-falling.
However there is another risk of it flying up and slamming into the ceiling for most types of lifts. For that kind of malfunction there is often no safe guard. A lot of lifts are of the type where they use a large weight which is about half the weight of the maximum load capacity of the lift. This weight is used as a contra weight and hangs in the elevator shaft (so it goes down if the lift goes up). If the brakes in the engine on top of the lift shaft fail there is nothing stopping the contra weight and the lift will fly up.
This is a YouTube video of that happening: https://youtu.be/Ys0rDAxdd-g (warning its not graphic but obviously a disturbing thing to see)
Back in university I had a side job as a security guard in an office building, when this happened. Someone took the cargo elevator, which was built to carry a higher load than the regular elevators, so it had a massive counter weight. The thing slammed into the ceiling with a bang that could be heard through the entire building, and the damage was quite extensive. Took a while for the guy to calm down as well.
in the European Union, nowadays, it is required to have a safeguard for "shooting up" as well[0]. If I recall correctly for quite some time it wasn't though. My Father who works in the elevator industry told me that in the GDR (German Democratic Republic) it was already mandatory but after reunification for some years Germany had more lax regulations til catching up again.
Most freight elevators are like that, though. So while that's a slightly horrifying diagram, a lot of people will have experiences what it's like being in on.
(In German, there's the word "klemmen" = to tuck, get stuck, get trapped, get caught; presumably it's a cognate. So, the above presumably is a Swedish word for "the risk of getting stuck and squeezed".)
My answer also meant to address that :-). I meant: There are plenty of technical ways to implement it (and the parent proposes a good one) but its not mandatory to do so, it costs money, and therefore its simply not implemented most of the time.
Elevators don't go into free-fall even if all the cables are cut at once. The safety chain is just one of the two or three safety measures.
The clack-clack-clack sound they reported was probably safety clamps attached to the rails. When the speed of the elevator exceeds some limit they start automatically breaking.
Kind of random and OT, but I remember a long time ago thinking about the safety of staircases. I was in a mall and on the top floor there was a movie theatre. To get to the movie theatre, there was a staircase which bridged the 4th and 5th floor. The staircase was literally a bridge that spanned over a central atrium. It wasn't suspended or supported by anything -- it only stayed up due to the rigidity of the structure. The movie theatre didn't like people crowding the lobby, so they had the queue go down the staircase. I remember thinking, "I wonder if the architects/engineers considered the possibility that there would be 3 people standing on every single step of this staircase". As far as I could tell there was no indication of what kind of load it could take. It never broke, so I guess they did think of it, but I never wen to that theatre. Waiting on that staircase was waaay too scary for me :-)
They do think of that. I've seen old bridges where extra barriers had been installed to prevent the full width being used because it was judged not capable of supporting the weight of being filled with people by modern standards.
There were a series of issues with the Hyatt Regency walkways, and at this point I'd expect every structural engineer knows the story.
1) The engineer designed something that was not easily buildable. (The bridge had to be jacked 2 stories up along threaded rods that supported it, and nuts rotated up that distance)
2) The contractor modified the design in the shop drawings to make it more buildable, (split the threaded rod into two sections, with the lower half hanging from the upper walkway) but in doing so doubled the stress on a particular piece that itself was replaced by a less capable similar item. (box section vs welded C sections)
3) The Engineering firm signed off on the change to the shop drawings without realizing the significance of the changes.
Even before they made that sloppy change that halved its strength, their design only supported 60% of the minimum rated load required by the building code. It was bad engineering from start to finish, and the engineers involved lost their licenses as a result.
You say that, but there will be a document somewhere telling people what the requirement is, and it will probably NOT say "Imagine the maximum possible amount of people that could physically fit, now add ten percent". And you might even find you need to track down the rationale in the engineering paperwork to know if the structural engineer envisioned this as a route crammed full of people or just a fun decorative element of the building that would technically be open to the public but rarely used. Not everything, build everywhere has to obey the same loading rules, many private homes have stairways that would be far too narrow, steep and poorly lit to be legal in commercial buildings for example.
When there was a balcony collapse in a foreign country I got interested and read the code where I live, the building regulations specify that a balcony or similar structure, which essentially hangs off the side of a building and so is unsupported at one side, must handle up to a certain load per square metre. Enough that a modest residential balcony can certainly hold two lovers, someone's spare bicycle and the decorative concrete flower beds they've put down to make it feel "outside". But what if instead of two lovers standing under the moonlight it's as many of the university rugby club as will physically fit? Ah, well then you're going to exceed the designed capacity and a code-compliant balcony might very well collapse.
All those tower blocks in England that are being retro-fitted because of the ones that burned down in London, their architects would have told you at the time they were definitely built to code, no extraordinary risk of fire. Then a bunch of people die in an out-of-control tower fire and - surprise - the politicians now claim the code meant you shouldn't ever have done that, and those towers were all built wrong but now they need to "clarify" the meaning. Sure.
I'm a software developer :-) What we usually call "software engineering" often doesn't take these kinds of issues into consideration. Even when I've worked with actual engineers (including P.Engs) the amount of "engineering" I've seen in my career as been vanishingly small. For example, I've worked in real time systems and we've had a performance budget. The number of times I've asked, "What did you do to ensure this will fit in the budget" and had people reply with something like "My code is fast. I don't think anyone can make it go faster" is ridiculous. Over time I've developed a kind of doubting attitude -- unless I see some evidence that you've done the due diligence, then I assume you've not.
Of course, what's common in my industry would obviously be fatal in other industries. I often tell my wife, "I don't have an unreasonable fear of heights. I have an unreasonable fear of engineers" :-) Still, I haven't died from having a bridge collapse under me yet, so I must be doing something right!
I know exactly what you mean. I used to work with someone who would constantly ask "where's the engineering? meaning where are the calculations, the data that support the conclusion that something would work? Refreshing words to my ears!
JFYI (and it may depend on each country's building regulations) -anything (being it slabs, rooms, corridors, terraces, staircases) in "public" buildings is required by norm to be calculated for a "dense crowd" (cannot say if that is the proper term in English) which equates usually to between 400 (static) and 600 Kg/m2 (dynamic).
This roughly equates to 4-6 people per square meter.
Because the elevator decended 84 floors doesn't mean the cable snapped immediately at the start -- express elevators are fast and shakey, there's no way to determine at what floor the cable actually snapped.
It could have accelerated too fast, and the cables snapped only when it started to slow down, which it probably would have anyways for the remaining 10 floors. they may have only free fell one or two floors, if at all. Cable probably snapped just before they started to hear the clack clack clack
While it must have been a terrifying experience - the headline makes it sound like the thing fell 84 floors to Zero - it actually stopped at floor 11 so the safety mechanisms kicked in. Thanks goodness.
True, thought the fact that it took 84 floors for the safety mechanisms to kick in seems problematic. What heuristics did those automated mechanisms have to work through before triggering, and why did they take 84 floors to do it, I wonder.
Clearly, it didn't take 84 floors for the safety mechanisms to kick in. If it had, the passengers would have been in free fall for 84 floors, and suffered the same physical consequences as you would if you jumped off the 84th floor of a building.
Falling 84 floors isn't less dangerous if you end 10 stories above the ground than it is if you end on the ground.
Yeah, I was really hoping the article would address this. Were the safety measures designed to kick in at the 11th floor, or were the passengers just lucky that they were at the 95th floor instead of, say, the 80th floor when the elevator took 84 floors for the safety measures to stop the elevator?
My guess is that there's some sort of velocity/acceleration threshold. So since the elevator car was still attached by other cables it didn't fall fast enough to trigger the mechanism earlier.
That, and this was an express elevator, so safety features have to kick in at higher speed.
Safety features also can’t decelerate the cage too fast. If, say, the elevator fell from floor 70 to floor 40 before safety features kicked in, it makes sense to use most of the remaining space for deceleration.
I once spent an hour or so trapped in an elevator. It was a small building, only six stories or so. A bit of a rumble, and it was just stuck, a few inches out of alignment with the exterior door. I didn't know it at the time, but the elevator had actually fallen up, because it was counter-weighted and I was alone inside, well below its weight limit. It was very old and a relatively small building, so I had no idea that this happened, and I thought it was just jammed at my destination on the first floor.
The emergency brake had kicked in at the top floor, but the doors wouldn't open when misaligned like that. Most of the time I spent in there was the technicians (and, for some reason, they sent the police to talk to me) looking for me. I had thought I was on one of the lower floors, and that's what I told the person on the emergency phone, so they were looking for me in the wrong place.
The elevator was old enough that I guess it didn't have any mechanism for reporting its location, and may have even been a relay-controlled system, which explains why they couldn't find me. After they showed up, it took a fair bit of prying on both sides to get the doors to open. I was surprised when I left and found out that I had been on the top floor the whole time, as they didn't tell me until I was freed. Then I took the other elevator back down to the lobby with the technicians, showed my professor the card from the police officer and explained why I missed class.
The one thing I wonder while reading the article is how they managed to figure out where the elevator was if it was in a blind shaft - they couldn't just go from floor to floor listening like they did for me. I used to live in an apartment in at all building that shared a wall with a blind elevator shaft, and I didn't even realize it for a while because the walls were so thick that the shaft was silent.
The article says they were in a blind shaft, which made the rescue more complicated. In the WTC bombing (http://www.interfire.org/res_file/pdf/Tr-076.pdf), there were also many people stuck in elevators in blind shafts, also complicating their rescue. Perhaps there should be a requirement to have an inspection access every other floor on blind shafts, to make rescue in these situations easier.
“This is the second most important building in Chicago? And this is the third most important city in the United States?” he questioned.
By what metric is Chicago the third most important city in the United States? I'd argue that NYC and DC are the top two (not necessarily in that order) and either San Francisco or Los Angeles (or both) also rank above Chicago.
I have a good friend from Chicago and IMO the midwest is a bit of a cult and Chicago is the epicenter of it. The practical result of this is a lot of local pride in Chicago. Chicago is the city that represents basically all of the Midwest from an urban perspective while other regions usually have multiple epicenters.
I can't find the stat at the moment but I believe there's an abnormally high return rate for people born in the Chicago area to come back to it. It's even very cyclical where young people live in the city, then they move out to the suburbs, have kids who go to college somewhere like OSU or Michigan then come back and work in Chicago and the cycle repeats. Nowhere else really has such a clear cycle like Chicago does, and I think it's because of the way Chicago is viewed by people in the area. Don't get me wrong it's a solid city but in terms of cities in the US I'd want to live in it probably comes out to #6 or so. In importance, I'd agree with your assessment as well.
All of this to say that I think Chicagoans find some odd reasons to put themselves high up in importance. I've heard a lot about O'Hare being the air travel epicenter of the US where every connecting flight goes through, the (now fading) financial epicenter Chicago used to be, a top food scene, the list goes on. I think it has local importance and I think locals have a bit of a chip on their shoulder about others not viewing it as being so important.
Edit: It's unclear if this is a local or international tourist in this specific case. Curious what the perspective is for an international tourist on the criteria.
> All of this to say that I think Chicagoans find some odd reasons to put themselves high up in importance.
This comment doesn't ring true in general.
My experience is that most Chicagoans usually correctly rate their city. Chicago has been historically perceived as one of the great American cities, with indisputably great achievements (Chicago architecture, economics, transportation, mercantilism, etc.). And today, people love living in Chicago because it's a major cultural center that has many things to offer over smaller U.S. metropolitan areas, while still being much more affordable than coastal cities.
But unless they are very young, immature and non-world-savvy, most Chicagoans usually also confess there are problems with crime, crooked politicians and (ever increasing Cook County) taxes. Chicago today feels like NYC in the late 80s, but with modern infrastructure.
Not that many Chicagoans will gush unreservedly about their city. Chicago is not the kind of city that invites unexamined boosterism.
I absolutely agree it's had more importance historically, but many of the things you listed don't have much relevance for what people define as an "important" city today. The central location of Chicago I think plays a lot into many of those factors re transportation and mercantilism in particular which aren't as relevant as travel became easier and the internet arose.
In terms of cost, in my experience, it's in line with coastal cities overall besides SF/NYC, maybe a bit lower than Boston.
> Not that many Chicagoans will gush unreservedly about their city. Chicago is not the kind of city that invites unexamined boosterism.
I wouldn't say they gush, but I know a good deal of people from the Chicago area at this point and it's very much in my experience an underlying assumption set they hold.
But population doesn't (in my opinion) determine importance. For example, the capital is a very important city even if not the most populous.
That said, I'm basically questioning an off-the-cuff quote made by a friend of someone who was in the elevator. The speaker should be forgiven for being imprecise…
> But population doesn't (in my opinion) determine importance. For example, the capital is a very important city even if not the most populous.
It goes the other way. Importance determines population. If the capital is not populous, that reflects the fact that the capital isn't especially important.
But assuming you're in a more or less steady state, that effect has already happened, so it's perfectly valid to just assume that importance and population are tightly correlated. The directionality doesn't really matter to the result.
Does it though? You still have provided no supporting arguments for that. People live in places for reasons beyond importance. In fact, "importance" really isn't a factor people consider when they decide to live somewhere at all really in my experience.
> For example, the capital is a very important city even if not the most populous.
> and either San Francisco or Los Angeles (or both) also rank above Chicago
Wouldn't it be Sacramento in this case, as the capital but not most populous city? The most important city is a combination of multiple factors: size, economic or political power, and probably some more (like cultural).
No, Sacramento is pretty insignificant in terms of population and economic power compared to SF and LA (and cultural aspects). Political power is also tied to population - LA and SF decide who sits in power in Sacramento. DC is an exception because it draws lobbyists and politicians there; state capitals usually don't.
> The author used population as criteria for importance.
There's no evidence for that anywhere, nor is this the author. This is a quote from a friend of someone in the elevator and there's no given criteria, so we can only speculate.
This is a person being quoted about the event, not the paper (local or WaPo). I don't think there's really much rhyme or reason here, I'd bet it's just what the person casually thinks about Chicago's importance.
No, but I haven't lived in many cities on that list. No, it's not a perfect assessment but the assumption that "X city is top and anyone who disagrees clearly hasn't lived there" is a perfect example of the attitude I'm talking about originally.
I may not have lived there but I have spent a good deal of time in many cities. I have explored various neighborhoods in these cities (Chicago included), regularly use their public transit, looked at COL numbers and done apartment searching in them to see prices, etc.
Thanks for the frank perspective! I'm a California native currently in my first year of college in the Midwest, so I'll have to keep an ear out for this attitude about Chicago.
I think this will turn into a pointless debate quickly unless someone nails down what defines the importance of a city. I don't personally think GDP is a defining factor. DC is a prime example against that.
For the record, I'm not putting Chicago far down on that list - it's probably around #5 (behind NYC, DC, SF, and LA). But I think this discussion came from the very casual assumption of someone to put Chicago #3 which I do think is interesting to see where that came from.
Why do you assume mine maps to nothing? Are you really arguing that the importance of cities is based off a single economic number or simply the number of people living there? I would say it's a combination of politics, cultural relevance, and economics mainly. Going down 1-4 in no order:
New York - huge center of mixed cultures, huge both population and economic output (larger than Chicago), and a big center of the fashion industry, art, etc.
DC - Capital with lots of political relevance, still good sized and has lots of other aspects that make up a city like good public transit
SF - The tech center of a world being increasingly run by tech, for better or worse
LA - Huge global entertainment hub, huge cultural mixing pot, huge GDP and population
I find this strong backlash interesting as I have no dog in this fight - I'm from a no-name suburb to a medium city in the south and am simply a lover of cities comparing what I have encountered.
I live in SF and have for years. My partner was born and raised here.
There are tech companies in SF but it’s vastly dwarfed by FAANG in SV. You could argue SF is a suburb for SV but I’m not sure how that would make the city any more important or interesting.
Due to insane housing costs you’re more likely to meet a younger person born and raised in the Bay Area in some Midwest city (like Chicago) unless they’ve decided to live with their parents.
The interesting culture of SF is in rapid decline. So what you end up with is a dying culture in a city funded by tourism (also in decline because of chronic homlessness) inhabited by transplants who don’t work in the city.
Is that important? I don’t know? Maybe it’s an important model of how not to run a city.
everyone can have their own importance mix for sure. Someone could find Anchorage, Alaska the most important ( and I say that without irony ). But if you want to talk to other people and use the kind of shorthand that all people understand very quickly, then GDP and population are pretty good indicators of importance that everyone sort of agrees to use as the proxy.
I'd say that cultural and political significance, while not as straightforward/objective to judge as GDP/population, are very much factors that are/should be in the layman's shorthand.
yes, but "cultural and political significance" are hard to define and so two people could easily talk past each other, because they would define these differently
whereas gdp and population are
a) easy to define and
b) correlated with significance
The Chicago metropolitan area is not only the third most populous in the U.S., it also has the third highest GDP by a fair margin.
More generally, it tends to be regarded as a much more global city than SF or DC. New York is clearly #1 as far as international importance, but Chicago generally places third behind LA in any serious ranking of U.S. cities based on economic and cultural importance.
What is the metric for ranking? By my metric, DC doesn't really qualify as a city - it's a giant barely functional suburb. Most metro areas in the US would seem to be similar.
But my ranking is irrelevant really. Most silly rankings like this put chicago around #3 based on population/GDP/transport/etc.
For me - it's one of maybe 3-4 cities in the entire US where you can live comfortably without a car - meaning there is at least semi-competent public transportation at a "World City" level. LA, SF, and DC don't qualify at all by that metric so I'm not sure how useful it is :)
I guess in my minds eye I put the "top 3" cities in the US as NYC, LA, Chicago in that order - but it's also based on somewhat dated and historical information.
Presumably the cabin didn't move too fast. An elevator doesn't just snap a cable, drop 84 floors in freefall, and only /then/ apply the brakes. A lift isn't suspended by a single cable in any case, it's suspended by 7. I suspect the media is making this all sound a lot more exciting than it was in reality.
You can look at it from another point of view: elevators have so many safety mechanisms nowadays that they can fall 84 floors and still not cause any injuries to their passengers.
Per mile travelled, (modern) elevators are literally the safest form of transit ever developed by our species. They are rather impressive devices from a safety perspective, somebody else linked the video in the thread so I'll chime in and say I highly recommend the defcon video "From the Pit to the Penthouse".
> Per mile travelled, (modern) elevators are literally the safest form of transit ever developed by our species.
Aeroplanes are at 0.05 deaths per billion km. There are around 30 deaths due to elevators in the US each year. So for elevators to be safer people would need to be traveling 600 billion km in elevators each year. The population of the US is around 300 million, so each person would need to average 1000km a year, or around 3km a day.
Even people in tall skyscrapers probably don't hit that number on too many days.
Definitely, I don't think aircraft can be beat on a fatalities/distance basis given not just their sheer distance covered by their uniformity and professional standards of maintenance. There are still plenty of ancient elevators around, and plenty that don't receive the upkeep they should (granted that's always been an issue for a lot of general infrastructure). That said elevators are still pretty safe, and are you sure that "due to" part is appropriate to use in a passenger perspective thread?
>There are around 30 deaths due to* elevators in the US each year*
I last looked at it many years ago so I don't have current sources, but the numbers presented by the US Bureau of Labor Statistics and Consumer Product Safety Commission indicated that around half the deaths (14/30 at that point) were those working near or with elevators, not the passengers. That is of course an important issue, but it's also a different one then in-use operational safety mechanisms, and I don't think airline rates cover on the ground maintenance deaths either. That stats I remember from around 5 years ago were that there were something like 900,000 elevators operating in the US and about 18 billion trips a year. So in terms of "get on the moving box, arrive safely" they still look pretty good.
All this is US centric granted, it wouldn't surprise me if there are countries where elevator deaths are much lower, though then again I'm sure there are places where maintenance is worse too. Aircraft are somewhat unique from a safety perspective in terms of not just themselves but the entire system built up around them worldwide.
> I last looked at it many years ago so I don't have current sources, but the numbers presented by the US Bureau of Labor Statistics and Consumer Product Safety Commission indicated that around half the deaths (14/30 at that point) were those working near or with elevators, not the passengers. That is of course an important issue, but it's also a different one then in-use operational safety mechanisms, and I don't think airline rates cover on the ground maintenance deaths either.
Sure, but I decided it didn't really matter since I don't think that people in the US even average 100m in an elevator every day, so even if only one person died every year aeroplanes would still be safer.
The other option for "safest vehicle" I considered was spacecraft. Even though they have a high mortality-per-journey I thought that maybe they travelled so far that they would come out looking pretty good per-mile. But, as it turns out, the moon isn't far enough away.
Looking at wikipedia [0] they also list deaths per billion journeys and per billion hours. Following on from your assumptions, these give the following:
At 117 deaths per billion journeys, only 256 million would be required, which would be fewer than one journey per person per annum. So lifts are much safer per journey.
For 30.8 deaths per billion hours it would be just under a billion hours needed (or 3.25 hours per person per year, ~0.5 minutes a day). I would imagine per minute this would put lifts and air travel at a similar risk per minute.
Wikipedia doesn't state if these are for general aviation or just commercial operations, which would skew the numbers considerably.
It's funny that many workplaces encourage using the stairs for health and fitness reasons, when you're much more likely to suffer serious injury or death in a slip and fall on the stairs than getting hurt in an elevator.
Yeah, I'd be way more interested in the safety mechanism behind how these people got out unscathed vs the rescue effort. This is really impressive engineering.
I was browsing through a list of elevator accidents a while back and noticed that the two main causes of death seemed to be people stepping blindly into empty elevator shafts and people who tried to get out of the elevator when stuck.
So, my recommendations for elevator safety are: watch where you're going, and wait for help to arrive if there's an elevator malfunction.
I never understood the stepping into an empty shaft, because AFAIK the outer doors are opened by the inside doors on the car. So they can't open on their own if the car isn't there. Might be possible on older elevators with manual doors?
There can be an open door to an empty shaft when the elevator is undergoing maintenance. This happens sometimes in the high-rise building where I work. Normally the area around the open shaft is blocked off with some kind of barrier during maintenance, but I suppose that the mechanics could forget to put up the barrier out of negligence or someone could disregard the barrier and walk past it. It's also possible that the people who fall into the shaft are the elevator mechanics themselves rather than passengers.
It's been a while and I'm not sure which list I had read. It may have actually just been a few incidents that struck me as easily preventable. I think they were mostly due to maintenance in progress or pushing against the doors.
Looking over this list[1], it's interesting how almost nobody in an elevator ever dies. The worst incidents tend to involve people or objects that are halfway into the elevator.
Otis said in a PBS special that the only people that die in elevators in the US anymore are people that work on them, unfortunately, but even that is only a few each year. I do remember an accident several years ago at Ohio State where some students were crushed at a dorm by trying to stuff it full. Anyway, like others have said, they're statistically safer than many other things.
Cable elevators are one of the safest vehicles you can be in. In fact, I wouldn't be surprised if they were safer than taking the stairs. There are so many redundant safety mechanisms in there you should feel extremely safe.
As long as you don't step into an empty shaft or fuck around with the doors if the elevator is stuck between floors your risk of injury is just about 0. The lift in the article didn't fall 84 floors, that'd have kicked in the governor. A lift is still perfectly safe if a single cable snaps.
My intuition is that no elevator could destroy its building even in free fall. Considerations: terminal velocity (air drag, weight, friction on the rails), mass, the surrounding part of the building, etc. Even a very heavy elevator in a half mile tall building would seem to be relatively low energy.
10,000 kg hitting at 400 km/s is equivalent to about the energy of 15 kg of TNT. The first WTC bombing was much more and the building withstood it.
Also I'd like to point out just how scummy this site is. The paywall offers a "Premium EU Ad-Free Subscription" with the following perk:
> No on-site advertising or third-party ad tracking
But trying to buy it paints a whole different story:
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https://www.youtube.com/watch?v=1Uh_N1O3E4E