A computer meltdown that knocked out Montgomery County's ability to control its approximately 750 traffic lights last month was caused by the failure of computer equipment that was more than 25 years old, county transportation officials said Monday.
But even with a fast-tracked schedule to overhaul the old signal system, a permanent fix won't be complete until about June 2012, they told a County Council committee.
"Every day that goes by, the risk of failure goes up," Traffic Engineering and Operations Chief Emil Wolanin later told The Examiner.
The county has been modernizing its 1981-era traffic light system through a $34 million project approved in 2007. It was supposed to be finished in 2014 but has been sped up since the breakdown caused gridlock on county roads, highlighting the age of the mainframe that coordinates the county's traffic signals.
The computer had crashed just before midnight on Nov. 3. Crews were able to restart it, but it crashed again by 3 a.m.
It took until 11 p.m. Nov. 5, nearly two days later, before all lights were reconnected.
County officials insisted on Monday that the computer failure was not a safety issue, as the lights did not go out. Instead, the traffic signals were not synchronized during rush hour, meaning that driving along busy commuter routes was worse than usual.
Crews tweaked some 200 lights by hand, coordinating with a traffic-scouting airplane and bus drivers about the locations of road snarls.
Inside, workers isolated a problem with how the computer interfaced with the light system. They tracked down a retired contractor and walked him through the troubleshooting to make sure they were on track. "We confirmed everything we were seeing," Wolanin said.
They replaced a part to make it operate again. Since then, crews have put backup equipment at 200 intersections so the lights can stay on time without a central computer system, Wolanin said. They plan to update another 200 more.
They also have installed about 35 battery backups, he said. And they repaired the failed part to keep in reserve.
The system has 300 miles of cable throughout the county, making a complete upgrade time consuming, Wolanin said. The county is seeking federal money to help pay for the work.
Some questions remain unanswered.
"Why did this happen?" Council President Nancy Floreen asked. "Is it in the 'stuff happened' category?"
Wolanin said it was not worth investigating why the old equipment failed. "The system is at the end of its useful life," he said.