DES MOINES, Iowa — We're a few weeks removed from the December snowstorm that brought bitter cold and blizzard conditions to parts of the state, but the impacts left behind are already being uncovered.
Potholes are caused by drastic temperature swings above and below freezing.
"You get melting of snow and ice that settles deeper into the pavement and the cracks," said Jonathan Gano, director of Des Moines Public Works. "In the overnight hours, that freezes and expands, and the next day it drops a little further into that new crack that's been created. The process then just repeats itself."
That's why Des Moines Public Works crews are out working on patching "every single mile" of the 750 miles of snow routes, according to Gano.
However, taking care of those craters is tough to do in the winter.
"The only material that's available in the scale that we need it is cold mix asphalt," Gano said.
Cold mix asphalt is easy to shovel into the holes, but it's a temporary solution because it doesn't set up and "grab" to the edges of the pavement.
Hot mix asphalt is the more permanent fix. However, DMPW can only put two or three tons of it per day out on the roads before the trailer that heats it up for application runs out. Additionally, it can only be used on warmer winter days.
When the more consistent warmth arrives in the spring months, crews can punch the potholes out once and for all — at least, until next year.