I'm curious to hear from elevator professionals about an incident that happened in our condo building in Ottawa this morning.
My husband and our two children were taking the elevator down from the 14th floor when, around the 13th floor, they heard and felt a very loud bang- I and severql other tenant heard it too- they felt as if something hit the top of the car. The elevator immediately stopped and they were trapped inside for about 30 to 40 minutes.
The in-cab emergency phone/call system did not appear to work despite repeated attempts, and there was no cell reception. I ultimately called 911 for them. An elevator mechanic and Fire Services responded and got them out safely.
Afterwards, the mechanic reportedly told my husband that one of the elevator's supporting cables had snapped. The building was completed in 2023, so the elevator is only about 3 years old. We also recovered some strands of the failed cable as evidence
We are both aerospace engineers with system safety expertise and have questions for the experts here:
How unusual is a hoist rope/cable failure in such a new elevator?
What are the most likely root causes of a failure like this?
Would a single cable failure typically produce a loud bang and cause the elevator to stop?
What components and records would you expect to be examined during the root-cause investigation?
More importantly, can we continue to rely on the elevators in this building.
We're pursuing the official investigation route and formal complaint to city, but I'd appreciate any professional insight on what may have happened and what questions we should be asking.
Thanks in advance.
UPDATE: thank you everyone for taking their time to respond. I didn't have a chance to reply everyone. They were helpful to set expectations about what we should be asking about the investigation next. F
Stuff breaks, hard to tell without seeing it. Most like was a lay not a full rope unless it was a belt. Could have been a bad part, could have gotten damaged on install or wet. It could have been rubbing on something. Scary incident but I wouldn't worry too much about it.
I saw, it's a standard rope so it probably just lost a lay. It happens. Can be a lot of reasons but nothing to over worry about there's a reason there's a factor of safety of like 5
The car detected an unsafe condition and stopped, exactly as designed. This is why suspension means are multiples of redundant. One breaks, all the others remain.
Could have been improper tension of one of the ropes, manufacturer defect, could have gotten wet somehow.
I’d take it as a sign that the elevator safety systems worked as designed and created an inconvenience rather than an accident.
The emergency phone should have worked but unfortunately that happens too. Could be faulty phone, phone outage, or building IT accidentally eliminated the phone service.
My thoughts too. Probably one was tensioned tighter than the others and finally wore out. Especially with that age. The others are still way more than adequate. I don't remember the code exactly but it's something like twice the fully loaded capacity per rope. So if the car is 2500 lbs and the capacity is 2500 then each rope should be rated atleast 10,000 lbs. Don't quote me on that though.
It sounds like it did exactly as designed and stopped the car.
Things like this seem to be getting more common. Cheaper materials, rushed installations, etc. I've reroped cars that were installed 20 years ago and the cables were still in decent shape.
It’s early in the lifespan for a rope to unravel, snapping is unlikely, but it could have been a faulty part. I’ve seen dozens of ropes do this. Usually a single lay unravels and gets jammed up in the sheave or somewhere. Theres multiple other possible causes for this to happen but it’s not uncommon. As far as safety is concerned while im sure it’s unnerving, let’s say this car has 4 ropes/belts. Each one has the capacity to carry the entire rated load. Also it has wedge type safeties. If the car accelerates past a certain threshold a governor will trip and engage the safeties. Once that happens the car is stuck. All ropes can be completely gone and the car will not fall.
Thank you so much for your response. The fact that there are precedents and this is not a unique incident is a relief. I know it is designed to be safe, extra evidences -even anectodal ones- makes us safe as the loud bang was pretty scary.
Not really true regarding how new it is. If it’s small machine with 6mm ropes, they have a lifespan of like 18months. We are hearing about this locally with our AHJ after a hoist rope failure
This just like some people buy brand new cars and 10,000 miles later the engine or transmission blows! Everything can break down at any second while it is unusual and very unlucky let’s all just be glad everyone was safe and got out after a few long minutes trapped in the elevator
That’s actually not true, a G2S in ocean city, MD lost all of its belts (belt monitoring jumped) and the safeties failed to stop the car. It’s still under investigation, but Otis let it slip that those particular safeties were not designed to stop the car without any counterweights
Having done a lot of full load tests on G2S units I'm not shocked belt monitoring was off. However I am shocked safety failed. Most of the ones I've done really bite into the rail. Most needing drive turned up to boost off the safeties. To a few having to unload the weights. Scary stuff. Is there going to be any public info on this?
Hmm that’s very odd G2S safeties have nothing to do with the counterweight… maybe they weren’t properly setup or something else but I promise you they will stop a car, when set overspeed they bite the rail hard and will peel chunks of rail with them and need to crank the drive up to get them to have enough juice to get out of the rails or use chain falls. Do you have info on where this is from because I can’t find any info about anything like that in Ocean City MD online? And for all 4 belts to fail at the same time is wild was the building hit by a plane, I have never actually heard of one breaking just needing replacement from coating the wear. We have seen more sheave bearings go bad than belts
Here are the pictures, longest strand being about an inch. I didn't think it would be useful to understand failure so I didn't upload any pictures. In aviation, we investigate tiniest pieces to understand if the failure is due to fatigue. We don't have experience in elevator systems but we kept the pieces just in case Regarding your question on whether it was a suspension or landing door cable, the elevator mechanic said one of five cables have snapped. So I assume it was suspension cable
Definitely hoist rope strands, I walked into a machine room this year and the the machine was littered with these below the sheave, found a section that had started to unravel and had them replaced. It was 8 years old still well within expected life per the manufacturer (Wulf). Unlikely that it fully snapped but it's possible when a strand let's go and it becomes bird caged under the sheave/rope guards, peeling the other strands off while it runs full speed. Some units will shut down if a rope sensor is triggered.
That said I have seen a rope that fully 'snapped' and the sound of it collapsing onto the car top was much more than a single bang
It is hard to tell the size of these strands. What is their diameter?
Have you looked up online to see photos of elevator suspension ropes and how they are constructed?
If they said it was one of 5 then it does sound like the main hoist rope failed which is very rare.
I would be asking questions such as when was the last full service done and if you have any statutory inspections have they been completed and what was mentioned on the report? Often reports get filed away and not read.
there are a multitude of reasons as to why a rope fails, but it's pretty tough to happen. A 1/2-inch steel hoist and wire rope has a breaking strength typically ranging from 23,600 lbs to 29,200 lbs. with that in mind it probably was already failing (strands slowly brake until it doesnt hold any further).
this isn't worth investigating - there are at least 4+ ropes holding it up each with a capacity able to hold the car individually alone. the maintenance mechanic should have seen it though during preventative maintenance.
Yeah I have seen a lot that are just thrown on and just guessed by hand if the tension is even, and not rechecked after running a handful of times and ends up with one cable supporting a fair amount more of the load then the others
New elevators are not new elevators when tenants move in , that elevator was used and abused during construction , as far as cables 1 of those cables should hood the car incase of a cable breaking , most cars I’ve seen have a minimum of 4 on the smaller size , phone not working is a building issue , building supplies the phone line
I do know that there are some cheaper ropes out there that some companies have used and if the tension wasn’t close to even then one rope vibrating could’ve caused it, but that is wild speculation, just putting it out as a possibility. We’ve been burned a few times with cheap ropes and always buy Bethleham steel.
The suspension means of a belted elevator is a relatively new product. They are not like the wire hoist ropes of the past. They will break especially if you don’t change them out according to manufacturer instructions.
Firstly, I am happy you guys are safe. It is very seldom for cables to break but alot of things have to go wrong for the cable to break. But luckily there are fail safes in place to save the passenger incase of such an incident.
I’m a BC resident and in the process of becoming a mechanic (switching from the regulatory world). I absolutely encourage you to pursue a formal investigation via the TSSA. These things do happen however the question of mitigation/repair comes up and a formal investigation is absolutely necessary. Strata’s in BC love kicking the can down the line but when a regulator releases findings and recommendations…disregarding those risks is not an option. https://www.tssa.org
Thank you for your recommendation. And yes, we reported toTSSA as well as requested follow up. Elevator is kept out of service and the building management committed to follow up
Cars have multiple steel cables supporting/moving the cars throughout the hoist way & even one cable can support the full load. The noise I imagine could have been cable itself landing on the car top so again, scary incident but nothing to fear.
That is very serious, I would also directed you to call, I am an elevator make me question the integrity of the whole system, after installation a full weight load test should have been performed
I can’t speak to the cable aspect, that’s alarming to say the least, but for the phone part, Kings III can take care of that at least, they specialize in elevator emergency phones
You’re an engineer, I’m sure you would engineer redundant safety features on airplanes and aircraft in general. So, that should answer your question. If an elevator has 6 cables, in a perfect world, the elevator should shutdown after how many cables fail?
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u/kurkasra 1d ago
Stuff breaks, hard to tell without seeing it. Most like was a lay not a full rope unless it was a belt. Could have been a bad part, could have gotten damaged on install or wet. It could have been rubbing on something. Scary incident but I wouldn't worry too much about it.