Traffic cameras along Ga. 400 that were on the blink Thursday and most of Friday, putting a primary anti-congestion weapon out of commission, are back online.

Mark Demidovich, a traffic engineer for the Georgia Department of Transportation, said a cut fiber optic cable that caused the outage was repaired just before 6 p.m. on Friday.

Commuters across the region use the information from metro Atlanta’s highway cameras and traffic monitoring systems to plot their daily drives, checking Georgia-Navigator.com or calling the DOT’s Transportation Management Center to find out which stretches of road to avoid. The cameras are central to a major regional strategy to combat congestion by “managing” traffic, since road-widening funds are not enough. Each commuter who avoids a traffic jam not only helps his own commute, but also avoids adding to the worst congestion.

State and local governments have poured more than $500 million in the past two decades into traffic management and technology, according to DOT. That money has paid for tools such as the cameras, highway ramp signals, remote signal timing and HERO units.

The author of a key national report on traffic congestion, Tim Lomax, cited Atlanta’s traffic-management tools as an important deterrent to congestion. At least, he said, it would be worse without them.

Unlike an outage that affected a couple of the cameras last week, this problem wasn’t caused by the theft of copper wiring.

DOT spokeswoman Jill Goldberg told the AJC Friday that the latest outage was due to a malfunction in the fiber optic network that relays the images from the cameras to the Transportation Management Center, after a contractor damaged the connection.

Officials at the Transportation Management Center initially told the AM750 and 95.5FM News/Talk WSB Traffic Center early Thursday that this week’s outage was due to the theft of copper wiring and fiber optic lines, a problem that has been plaguing not only the DOT but other government agencies as well recently.

Feeds from a pair of cameras on Ga. 400 at the Chattahoochee River in Sandy Springs went dark during the afternoon rush hour on Aug. 27, and when police officers checked on the cameras, “they realized copper and fiber had been stolen from a junction box,” Sandy Springs police Capt. Keith Zgonc said.

DOT spokesman Mark McKinnon told Channel 2 Action News last week that the agency was “having a real problem with people going out and taking that copper.”

“Having those cameras operable is important,” McKinnon said. “That’s what helps your average motorist get to work every day, that we’re able to see what’s going on out there.”

McKinnon said the thefts are also dangerous to the thieves.

“Someone could get themselves killed doing something like that,” he said.

Antonio O. Beasley, 48, of Atlanta was recently arrested and charged with felony theft by taking in the theft of copper wiring from about 50 light poles in Sandy Springs.