Curled metal fixtures are going up on a handful of Michigan Avenue light poles later this summer to record information about Chicago's people and surroundings.
The smooth, perforated sheaths of metal will house a system of data-collection sensors that will measure air quality, light intensity, sound volume, heat, precipitation, and wind.
The sensors will also count people by observing cell phone traffic.
Planners have taken precautions to design their sensors to observe mobile devices and count contact with the signal.
They say they will not record the digital address of every device.