Here is a news item from Cloquet, Minnesota that I found of interest. It involves an I-35 overpass accident that appears due in part to poor snow  maintenance. The way the accident happened should be a concern to state highway department snow clearing crews and the public in general. Snow that accumulated on an overpass appears to have created a ramp of sorts, that allowed a skidding car to be ramped up and over the side rail and onto the interstate highway below. The smashed up car created a bit of a conundrum for the police. When they arrived, the police found the car upside down with the roof crushed and pointing in the wrong direction on I-35. There were no skid marks and no other cars involved. The officer needed to walk up the incline to the overpass before he could figure out how the car got in the north bound lane.

Woman whose car fell off Cloquet bridge 'lucky to have survived'
Duluth News Tribune - The car landed where northbound I-35 and Minnesota Highway 33 merge. “The best we could tell is that it landed on its roof,” Vereecken said. ... See all stories on this topic »

Typically we assume we are fairly safe driving on an overpass, at the designated speed and also that the design of the road surface, the bridge railings and overpass structure will protect us from a fall. But in this case the woman plunged over the side rail of an overpass after skidding and then sliding up the snow bank, which by the way should have been plowed. She landed upside down on the Interstate; in this instance I-35 near Cloquet, Minnesota.

Now consider passing underneath an overpass and what that could mean to you.

"Honey is that car going to fall on us?"

Now I would agree that Minnesota gets a lot of snow, but this case is a warning to one and all who use the overpasses and typically see snow pushed up along the overpass side rail.

I'm assuming that maintenance issues will become a more serious problem as state budgets get worse. So be aware of what can happen and how accidents start.