3 ms·

Having gone through this infographic, one thing starkly stood out. 1. There was a 7 minute gap between the initial structural failure and the rest of the tower

Having gone through this infographic, one thing starkly stood out. 1. There was a 7 minute gap between the initial structural failure and the rest of the tower to collapse . 2. Due to the failure of the alarm system or something else, the alarm did not sound . 7 minutes is an eternally long time for people to get out had the alarms sounded correctly. May be the alarms were not designed to go off in the case of structural failure and only for fire etc ?

toast0 5y ago
> 2. Due to the failure of the alarm system or something else, the alarm did not sound . > 7 minutes is an eternally long time for people to get out had the alarms sounded correctly. > May be the alarms were not designed to go off in the case of structural failure and only for fire etc ? There was a linked paywalled article, the link text seems to indicate that alarm logs show the alarm was triggered. Not sure by what, maybe the article has details. I wouldn't expect some sort of collapse sensor in the fire alarm system, but when the pool deck collapsed, it may have released enough dust to trigger a smoke detector in the parking garage, or it may have disconnected sensors which could also be a triggering condition.
- JoeyBananas 5y ago
  Every commerical building I've ever seen has fire alarm levers on the walls. Somebody could have triggered the alarm manually. These fire alarm levers are everywhere, but they rarely ever get used in an emergency. If what happened is someone pulled the lever and the system logged it but the alarm didn't go off, that's a huge problem.
  - bsder 5y ago
    > Every commerical building I've ever seen has fire alarm levers on the walls. I see these very rarely nowadays. Apparently they get triggered too often as pranks, and it trains people to ignore the alarms. So, they don't put them in new construction.
tomatotomato37 5y ago
I don't think most building alarms account for a collapse that isn't the result of some other event like fire or earthquake, partially because keeping the alarm system running through the collapse is hard and partially through the mistaken assumption that the initial collapse would be loud/energetic enough to alert everyone in the vincinity.

toast0 5y ago

> 2. Due to the failure of the alarm system or something else, the alarm did not sound . > 7 minutes is an eternally long time for people to get out had the alarms sounded correctly. > May be the alarms were not designed to go off in the case of structural failure and only for fire etc ? There was a linked paywalled article, the link text seems to indicate that alarm logs show the alarm was triggered. Not sure by what, maybe the article has details. I wouldn't expect some sort of collapse sensor in the fire alarm system, but when the pool deck collapsed, it may have released enough dust to trigger a smoke detector in the parking garage, or it may have disconnected sensors which could also be a triggering condition.

JoeyBananas 5y ago
Every commerical building I've ever seen has fire alarm levers on the walls. Somebody could have triggered the alarm manually. These fire alarm levers are everywhere, but they rarely ever get used in an emergency. If what happened is someone pulled the lever and the system logged it but the alarm didn't go off, that's a huge problem.
- bsder 5y ago
  > Every commerical building I've ever seen has fire alarm levers on the walls. I see these very rarely nowadays. Apparently they get triggered too often as pranks, and it trains people to ignore the alarms. So, they don't put them in new construction.

tomatotomato37 5y ago

I don't think most building alarms account for a collapse that isn't the result of some other event like fire or earthquake, partially because keeping the alarm system running through the collapse is hard and partially through the mistaken assumption that the initial collapse would be loud/energetic enough to alert everyone in the vincinity.