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>This is why emergency exit doors must open outwards. People have died in fires in theaters trying to push on doors that said “Pull”. The crash bar on an emerge
by InvisibleCities 9y ago
>This is why emergency exit doors must open outwards. People have died in fires in theaters trying to push on doors that said “Pull”. The crash bar on an emergency exit door is what’s known in design as an affordance.
Is this true? I always assumed it was because it's pretty much impossible to pull open a door when you are being crushed by people pressing against one another trying to escape.
- piptastic 9y agoI think it's true to some degree, I've seen people push on doors that say "pull" even when there is no fire. But I think your assumption is probably more correct, past a certain point they have no option to pull anymore.
- jclardy 9y agoThe push/pull "mistake" is usually caused by poorly designed doors. Like putting a vertical grab handle on a door that pushes open.
- Angostura 9y agoDon’t worry about that. Just retweet it as a fact, pronto.
- gdubs 9y agoThanks - you correctly caught an error and I’ve edited the post to address it. The danger is in the confusing affordances, and the point was about that and not the direction of the door swing (which as you’ve correctly pointed out has other more primary considerations.)
- KirinDave 9y agoIt's the same sort of myth as "why are manhole covers round?" and there are lots of attributions for why that ignore history for a just-so story.
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- mulmen 9y agoI don't understand the reference. Why are manhole covers round? I always thought it was to prevent the cover from falling into the hole. Is that not the case?
- KirinDave 9y agoThat is the argument but actually any lipped shape can give this guarantee. Even historically manhole and utility covers had to be somewhat flush to the ground and so they've always had to be lipped for this. You can see lots of utility covers that are hinged, square, or other options, but all are lipped for safety. While a circular profile makes the lipping easier, it doesn't seem to influence many utility covers.
- anigbrowl 9y agoYou can easily put a square or a rectangular utility cover into the hole, because the length of the side is less than the diagonal. This isn't possible with a circular cover because the diameter is uniform.
- derefr 9y agoThe parent’s point is that a lip prevents this for every shape, by making the hole smaller than the side-length.
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- mulmen 9y agoOnly with a sufficiently large lip. The diagonal of the hole has to be less than the shortest side of the lid. As I picture it in my mind this is an excessively large lip.
- wizardforhire 9y agoYes and recent. >An inward-swinging door - three times cited as a code violation by West Warwick inspectors and three times replaced by club managers - was blocking the exit closest to the stage. https://www.bostonglobe.com/metro/2013/02/15/series-errors-sealed-crowd-fate/7m4vKomVXAhUTpQAODnLHN/story.html https://www.bostonglobe.com/metro/2013/02/15/series-errors-s...
- somecontext 9y agoFor some context in case anyone is curious, two sentences later the article reports that "Bouncers opened it immediately after the fire broke out". The door in question's main problem appears to have been that bouncers wouldn't let people use it, not its orientation.
- pbhjpbhj 9y agoAFAIK you're correct, a vertical handle is an affordance to that indicates a door should be pulled, but the reason is mechanistic. A crush of people will open the door with a push-release but won't with a pull handle - whilst the handle affords pushing some numpty will try and pull it but the people behind them will soon ensure that they push the door, with their broken ribs if necessary.
- sizzle 9y agoNorman doors https://99percentinvisible.org/article/norman-doors-dont-know-whether-push-pull-blame-design/ https://99percentinvisible.org/article/norman-doors-dont-kno...