re: Since Feb., New Orleans traffic cams issuing tickets at lower speeds; change unannounced

Compare the school zone times and the delta between the usual speed limit and the zone limit, depending on the thoroughfare, with those in other cities and I bet you'll find the that the NOLA traffic-planning is set-up for the driver to fail.

As for the technology, I have to believe that the specifications for the radar/photo sensors would require scheduled maintenance and calibration. I would question if there are any such records.