Park City-area stoplight synchronization fails, causing traffic backups
February 27, 2019
The system that synchronizes stoplights in the Park City area failed during the Tuesday evening rush hour, causing widespread traffic issues in Park City and the Snyderville Basin, a Park City official said.
The stoplights are connected through a computerized system designed to keep traffic flowing at appropriate rates on S.R. 224 and S.R. 248, the two state highway entryways. The only stoplights in the Park City area are on the state highways, and they are under the control of the Utah Department of Transportation.
Alfred Knotts, the transportation planning manager for City Hall, said UDOT lost communications with the computerized system. The loss of communications started at approximately 4 p.m., he said. The communications were restored at 8:35 p.m., meaning the failure occurred during the busy evening rush hour, when skiers leaving the resorts and workers leaving for the day converge on S.R. 224 and S.R. 248. Knotts said the traffic appeared to be back to normal flows by 7 p.m. since the number of vehicles on the entryways dropped by then.
Knotts said the failure caused the stoplights to revert to a mode that gives equal time for green and red lights in all directions, meaning that side streets had the same amount of time for a green light as the state highways themselves. The system when it is working gives green light priority to drivers on the state highways. He said the failure caused "significant" backups.
"It was treating all legs of traffic, no matter what the volume, equally," Knotts said, describing the backups as resembling a snowy weekend day. "It was a perfect Saturday or perfect Sunday with a storm."
He said the failure also impacted pedestrian-activated crosswalk signals along the two state highways, describing that the signals were triggered without activation by a pedestrian.
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Knotts said the failure was a result of an outage in the fiber optic system's server. He said the outage was "like when your internet goes down. It's that simple."