Why do cities install sensors and then ignore them?
The measurement worked. Nothing followed it. — 15 documented cases in this atlas, each linked to its sources.
The test: Did the instrument do its job, and fail because nobody was obliged to act on what it said?
This is the most common way a smart-city project disappoints, and the least visible from the control room: the sensors report, the dashboard updates, and no lever is attached to the other end. Chicago heard the gunshots and its own Inspector General could not say what the police response produced. Los Angeles ran crime forecasting for nine years and its own watchdog still could not measure what it changed. Miami-Dade lowered the temperature at which a heat alert fires, and then the state removed the county's power to attach any obligation to that alert. In each case the technology is not the thing that failed.
Two labels, kept apart. 2 of these are recorded as failed — stopped, cancelled, or demonstrably not doing what it was built to do — and 13 as scaled back, which mostly means a service that still runs but delivered materially less than promised. An entry earns either label only where a named source says so.
✔ Every published entry is checked against the public sources it cites before publication.
The 15 documented cases
The other five patterns
The whole record
Every entry in the atlas that failed or was scaled back, all six patterns in one place, with the arithmetic behind the share: smart city project failures.