LOS ANGELES (AP) a¿¿ In a story Nov. 23 about inoperative traffic sensors, The Associated Press misidentified the company that provides data to Michigan for its Mi Drive traffic map. The data is provided by HERE, a business owned by Nokia, not by Inrix Inc.
A corrected version of the story is below:
Dim traffic sensors dull how 'smart' freeways are
As more traffic sensors fail, blind spots develop on highways; headache for drivers, planners
By JUSTIN PRITCHARD
LOS ANGELES (AP) a¿¿ California's highways 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 and congested 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 the congestion that quickly builds before crews can get out and clear an accident.
A speedy response matters: Every minute a lane is blocked during rush hour means about four extra minutes of traffic. Fewer sensors can mean slower response times, so the fact that 34 percent are offline a¿¿ up from 26 percent in 2009 a¿¿ creates an extra headache in California's already-sickly traffic situation.
"(It) is not an acceptable number, really," said California's top transportation official, Brian Kelly.
With limited space and money for new lanes, Kelly said, maximizing flow on existing freeways is critical. To do so, planners rely on a network of cameras, above-road detectors, message boards and the in-road sensors called "loops" because of their shape.
Some loops were cut during construction, others yanked out by copper wire thieves. Many have succumbed to old age.
The resulting blind spots show up as strings of gray amid the green, yellow or red on the large map that freeway managers overseeing Los Angeles and Ventura counties monitor for signs of trouble. Even worse off than LA, according to Caltrans, are inland areas such as the San Joaquin Valley and San Bernardino and Riverside counties.