California's freeways aren't as smart as they used to be.
Buried under thousands of miles of pavement are 27,000 traffic sensors that are supposed to help troubleshoot both daily commutes and long-term maintenance needs on some of the nation's most heavily used roadways.
And about 9,000 of them do not work.
The sensors are a key part of the "intelligent transportation" system designed, for example, to detect congestion that quickly builds before crews can clear an accident.
Blame the malfunctions on old equipment, construction and even copper wire theft.
California is not alone—states including Utah, Texas and Michigan have struggled with sensors, too.
Explore further: Report: FBI's anthrax investigation was flawed