Dead disk kills traffic flow

Last year, central London traffic ground to a halt during the morning rush hour, due to a computer system that failed while engineers attempted to alter its software.

In Melbourne, Victoria, about 30 sets of traffic lights stopped working when a hard-disk failed. The disk was a vital component of Vicroad's SCATS system, which is designed to allow for the remote control of traffic lights from a central location.

According to Vicroad's traffic management centre's acting manager, Keith Weegderg, all signals are back up and running independently, although remote control of the lights could not be restored until about 1pm. The lights were manually switched over into a "stand-alone" mode by technicians, but that process itself presented some challenges, Weegderg said.

"They were stuck in the traffic like everyone else as well, so it took them some time to get to them," he told ZDNet Australia.

The remote-control system is nothing new, Weegderg said.

"We've had the SCATS system in Melbourne for 20 odd years," he explained. "It provides linking between successive sets of signals so that when there's event... we can change the timings of signals remotely."

Weegderg said he was unaware if further redundancy would be built into the system in the future, but that an investigation is taking place.

"This failure is quite an unusual one... we'll have a look at it and determine the follow up actions for it," he said.

Initial reports suggested the outage could have lasted for up to two days.