A perfectly comfortable public-use bench, with a clearly posted "30 minute time limit" sign. Once weight is detected, it begins a 30 minute countdown. When the time runs out, it vibrates for up to 15 seconds, then emits a loud, high pitched tone for up to 15 seconds. If the weight is not removed, the entire seat pitches down 15° and continues to vibrate until the weight is dislodged.-- 21 Quest, Oct 10 2024 What does it do if there is an overlap of people sitting on it for differing amounts of time, but when combined the bench detects as being longer than 15 minutes?-- xenzag, Oct 10 2024 Have it segmented, with a negligible but clearly visible gap between segments.-- 21 Quest, Oct 10 2024 Missed opportunity for a spring-loaded catapult.
Defeating it would simply involve moving to a different spot on it, or sranding for 3 seconds.-- RayfordSteele, Oct 10 2024 Why is it a problem if one person sits on a bench all day? This is just hostile architecture.-- 5th Earth, Oct 10 2024 More benches.-- minoradjustments, Oct 10 2024 It isn't hostile to say you have to move eventually to make room for someone else to be able to sit there. It also isn't hostile to say that one person isn't allowed to lay across a bench sleeping on it, taking up all 3 spaces for himself.-- 21 Quest, Oct 10 2024 Ignoring for the moment the ethical question of whether a person should be allowed to sit on a public bench as long as they like, the solution as described wouldn't work for the problem stated.
As Rayford pointed out, this could be defeated by just standing up and sitting down again. Which means it would only really work to prevent people from *sleeping* on the bench (a classic goal of hostile architecture), and even then only for 30 minutes at a time.
You could add some sort of time lockout to discourage this, where no one could sit on the bench for a length of time after the last sitter, but then you're just making a bench that can't even be used at all some of the time.
In any case, I guarantee such a bench would be vandalized into inoperability almost immediately by disgruntled ex-sitters and/or the wantonly destructive. Far cheaper and effective to just build more benches, as minoradjustments said.-- 5th Earth, Oct 10 2024 random, halfbakery