COLUMBIA — Columbia drivers aren't the only ones worn thin by the weather this winter. Potholes are a sign of the unusually cold season.
Both state maintained roads and city maintained roads use a temporary filler during cold weather. The mix is composed of asphalt and oils that work best for low temperatures. The permanent mix can't be kept hot long enough to be effective during the winter.
Jill Stedem, Columbia Public Works information specialist, said "hot mix" factories close during winter. When the factories open again in April or May, street maintenance crews redo temporary-mix fills.
Potholes are formed when:
- Moisture below the asphalt and precipitation contribute to thinning the existing asphalt.
- Fluctuating temperatures freeze and thaw the water, expanding cracks underneath the surface. Cracks in pavement allow more moisture to seep into it and cause further damage.
- Traffic and road debris chip away and put more stress on the asphalt
- Weakened asphalt eventually collapses, leaving a large hole
These factors play a part in how long the temporary fixes last; lower traffic areas with less moisture below the asphalt surface can last much longer.
When a pothole needs to be filled, several factors determine how and when it gets done:
- Plowing and salting roads is done first before attending to potholes, Stedem said.
- Severity is the most important factor. John Schupp, a Missouri Department of Transportation area engineer, said the deeper and wider the pothole is, the higher the priority for fixing it. "If it threatens safety for drivers, it's our top priority to fix it as quickly as possible," he said.
- Priority is determined next by complaint and location. The priority list for filling potholes is the same list that the city and state use for critical snow route maintenance. The amount of traffic, location and resident complaints determine the maintenance priority. Route maintenance can include plowing, salting, trash clean-up and pothole-filling as well as other services.
Compared to the last two winters, when the weather was milder and there was less precipitation, Stedem said there seems to be a higher number of potholes this year.
The Columbia Public Works Department has allotted $679,687 for street maintenance for the 2010 fiscal year. The account covers asphalt, concrete, trap rock, culverts and sand. Stedem said she had no estimate of how much of that money is spent on fixing potholes.
Schupp said potholes don't take very long to fill with the temporary mix. He guessed it's usually about five minutes from when the maintenance truck stops to fill the pothole to when the truck drives away.
Drivers can avoid damage to cars or tires by driving slower and avoiding potholes when possible, said Schupp. "We would ask that people please be patient and know that we're getting to them as quickly as we can."
A few tire repair shops have seen an increase in customers coming in with tire problems from potholes.
Cherelle King works as a service writer at the Walmart on West Broadway. She said two months ago they were selling about 10 tires a day. Yesterday, she said, they sold about 25.
Sam Botts, a salesman at Ewers Tires in Columbia, said there are a few preventative measures drivers can take to minimize damage to their wheels and tires. "Keeping tires inflated is important," he said. "Low tires are more likely to be damaged beyond repair."
“We’re trying to ask Columbia residents to be the eyes and ears for the city," Stedem said.
View Potholes in Columbia in a larger map