TUCSON, AZ (Tucson News Now) -
From New Year's Eve through Thursday morning, Tucson will be having cold nights, and that means the city and Pima County crews have been out treating the bridges to keep them from icing up.
City crews treated 57 bridges.
Pima County was out spreading magnesium chloride on another 40-plus spans.
The chemical keeps moisture from freezing and making it dangerous for drivers.
Tucson Interim Transportation Administrator Jose Ortiz says the city used about 400 gallons of magnesium chloride on its bridges.
He says, barring rain that would wash the chemical away, it should last about 10 days.
Ortiz says the city has a particular threshold when the decision is made to treat the bridges.
He says the Transportation Department looks at temperature plus dew point.
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