A bench that reports how long people actually stay

The brief was from a city parks team who wanted to know which benches earn their place. Every off-the-shelf answer involved a camera, which was both expensive and the wrong thing to put in a park.

The build uses four load cells under the slats and a capacitive strip along the back rail. Weight tells you someone sat down. The strip tells you they are still there. Neither tells you who they are, which was the point.

The hard part was not the sensing, it was the weather. The first enclosure filled with water in a week. The second used a printed gasket and a breather membrane, and survived the rest of the term.

It reports a count and a median dwell time once an hour over a low power radio. That is all it does, and that turned out to be all anyone wanted.