Ask a Trooper

Q:  Why do bridge decks freeze up faster than the rest of the roadway?

Sgt. Jesse Grabow

A:  Bridges are made of steel and concrete, which conduct heat well and the heat within the structure is released rapidly from all sides when temperatures drop. When the bridge loses heat while being hit with freezing wind and air from all sides it quickly responds, matching the dropping temperatures — leaving icy bridge decks.   I might add that bridges, by purpose, are often built above cold spots, like rivers, adding to this quick cool system.

A road doesn’t have as many avenues for the heat to escape and thus doesn’t cool as fast, being insulated from the earth below.  Additionally, asphalt roads do not conduct heat well and the response to frigid temperature is slower.

With that being said, we still have a lot of winter left and even though this has been an unusually warm and mild winter compared to most, this is Minnesota and things can change fast.  Be prepared for the worst.  Do not use cruise control on snowy/icy/wet roads and make sure to turn those headlights on when it is snowing/sleeting/raining/ or foggy. — Sgt. Jesse Grabow of the Minnesota State Patrol (Editor’s note: If you have any questions concerning traffic related laws or issues in Minnesota send your questions to Trooper Jesse Grabow – Minnesota State Patrol at 1000 Highway 10 West, Detroit Lakes, Minn. 56501-2205.  Or he can be reached  at, [email protected])