A city truck driver applied double the recommended amount of deicer on the West Seattle Bridge last week, resulting in slick conditions that led to wrecks and a two-hour road closure, Seattle Department of Transportation officials said today.
The Seattle Department of Transportation (SDOT) officials told a City Council committee that a “flusher tanker” driver dumped the liquid deicer, magnesium chloride, on the bridge at a rate of 30 gallons per mile, rather than the recommended rate of 15 gallons per mile. There were at least three accidents on the bridge, and the Seattle Police Department’s southwest precinct commander said officers saw additional fender benders that probably went unreported.
A Seattle Police Department sergeant on the scene made a decision to close the overpass around 1 p.m. last Monday, Dec. 2 so that SDOT could apply sand to the slickened roadway. The bridge reopened around 3 p.m.
“The dial was set at 30 instead of 15,” said SDOT director Peter Hahn. “It's really not that mysterious, the setting was wrong and a mistake was made.”
The manufacturer of the deicer — also known by its trade name FreezGard — says it can cause slippery conditions if used on surfaces that are warmer than 40 degrees. SDOT officials said that temperature-sensor data shows that bridge deck was about 38 degrees around the time that the truck driver applied the substance.
During Tuesday’s meeting, Transportation Committee chairman Tom Rasmussen pressed SDOT and Seattle Police Department officials about whether they were effectively using Twitter, texts and the media to inform the public about situations like the de-icing mishap.
“The public is really good about alerting people right away,” Rasmussen said.
“There was practically a moment-by-moment exchange of information going from the rest of the public to the West Seattle Blog,” he continued. “Can you connect into that kind of a system, or create that, so you can have that kind of information?”
“That’s one of the things we’re reviewing is whether there are blogs, and whether there are other resources in the city, that we need to be tapping into in the traffic management center,” said Mary Rutherford, director of SDOT's traffic management division.
Traffic management center staff members monitor the city's traffic control systems and provide information to the public using Twitter, the SDOT website and electronic signage. As it stands, Rutherford said, the center gets up and running each day at 7 a.m., and is staffed by interns and one full-time staff person. There is additional money in the 2014 budget, she said, that will allow the center to add staff and expand hours.
The first accident on the bridge was reported to the police department around 12:28 p.m. last Monday and officers arrived on the scene around 12:32 p.m., according to Southwest Precinct Commander, Joseph Kessler. “At the time they started to arrive they could see cars slipping,” he said. “Our officers, when they drove up, they were slipping also.”
With forecasts calling for several inches of sleet and hail by mid-afternoon, and freezing temperatures by 5 p.m. that day, SDOT officials made a decision to “pre-treat” the West Seattle Bridge, the Alaska Way Viaduct, the Aurora Bridge and other overpasses in the city with deicer.
“We were trying to be proactive and get ahead of what the various forecasts were telling us,” said SDOT road maintenance manger, Steve Pratt, who apologized and said that he took “100 percent” responsibility for the application rate error. SDOT's lack of action during a snowstorm is generally believed to have contributed to the defeat of Mayor Greg Nickels in the 2009 primary election.
Hahn, who is leaving his position before Mayor-elect Ed Murray takes office, reassured the council that FreezGard is safe and Pratt said that since last Tuesday SDOT has put down 9,000 gallons of the substance without any incidents. “It does work well,” Pratt said. “We’ve been using it for almost three years.”
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