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Comment by skaomatic | Hacker News Reader

This reminds me of an elevator's "Door Close" button. Manufacturers still include them for the peace of mind of passengers, despite computerized systems and many area laws (in the US, the ADA has language regarding door-open timespan for wheelchair access).

EDIT: Thanks to a_c_s for pointing out that the button can work when the elevator is in emergency/service mode. More fun information on elevators, crosswalk and other buttons can be found here: https://www.nytimes.com/2016/10/28/us/placebo-buttons-elevat...

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In my office (in Germany), when the elevator door opens and I hold the "close door" button, it immediately starts closing as soon as it's finished opening. So at least that one is definitely not a placebo.

Same here in the UK. Both the close and open buttons work immediately after being pressed in my office, so they're clearly not placebos.

Elevator "door close" buttons can fall into several categories.

1. They work as labeled, immediately closing the door.

2. They work, but only after door has been open longer than a threshold time, or only if the door open time has been extended using the "door open" button.

3. They work, but only when the elevator is in some special mode such as fire/emergency mode.

4. They are supposed to work, but broke. A broken "door close" button does not put the elevator out of service, and might not even be noticed at all (especially if it is a category #2 button) for a long time, and so a broken "door close" button can stay broken for a very long time.

5. They would work except they have been disabled by the owner, perhaps to comply with laws, or perhaps because there were too many assholes prematurely shutting doors.

6. They are placebos.

The door close button is used when the elevator is in fire service mode (where all actions are manually activated)

Interesting - and makes sense! A detail missed by my tour at the Elevator History Museum in New York, NY. [elevatorhistory.org]

They're not placebos in all cases. They definitely work in one tall bank building I worked in in Canary Wharf.

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