TUCSON, Ariz. — As temperatures in Tucson drop to freezing levels, the city has activated "Operation Freeze," a safety initiative designed to protect motorists by de-icing bridges.
Unlike regions that rely on traditional rock salt, Tucson’s Department of Transportation and Mobility, or DTM, uses magnesium chloride, an anti-icing solution, to prevent ice from forming.
“Ahead of the forecasted freezing temperatures, our DTM street maintenance staff go out and spray magnesium chloride on bridges,” said Erica Frazelle, the department’s Public Information Officer.
The proactive measure is critical, she said, as bridges are particularly vulnerable to freezing due to cold air circulating above and below the structures.
The city targets 55 bridges and bridge decks for treatment during freezing weather.
“You may not even realize some of these are bridges,” Frazelle noted, pointing out that even small wash crossings, are included in the program.
The solution forms a protective layer that remains effective for up to 10 days, though rainfall can diminish its potency.
Magnesium chloride offers several advantages over traditional rock salt, which is commonly used in colder regions.
“This allows motorists, as well as motorcycles, to drive safely over the bridge without that salt,” Frazelle explained.
Additionally, the solution is environmentally safe, as it washes away harmlessly into the city’s washes.
Frazelle emphasized the efficiency of the operation, which is carried out by three crews working across the city.
“Ahead of those freezing temperatures, crews go out and target different areas within the city, working for a few hours to ensure the bridges are safe,” she said.
The program, active since 2018, costs the city an average of $35,000 annually, with $20,000 spent on de-icing bridges last year.
“We’re continuously monitoring the forecast and ensuring that if there is a freeze, we apply magnesium chloride preemptively,” Frazelle said.
Motorists are urged to drive cautiously on de-iced bridges, as signs warning of “wet roads” are posted during applications.
“Give yourself extra time and ensure the safety of both our crews and yourself,” Frazelle advised.
Operation Freeze highlights Tucson’s commitment to driver safety, even in rare freezing conditions.
