AASHTO Journal, 5 February 2016
While states along the Eastern Seaboard were digging out from late January’s “Snowzilla” monster snowstorm, in the Southwest the Arizona Department of Transportation warned that this winter’s El Niño-fueled storms in that state are leaving ADOT and drivers facing lots of extra potholes.
“The good news is ADOT crews regularly examine state highways for potholes and address them as quickly as possible, making short-term patches followed by long-term repairs,” the agency said Jan. 29. “But conditions that lead to potholes will keep coming . . . meaning drivers should keep eye out. How many potholes develop depends in part on how much rain and snow falls.”
That is a big change from what Arizona drivers may be used to. ADOT said since the state has experienced drier conditions over many of the past 15 years, fixing potholes hasn’t been as much of a challenge. But that could change this year, depending on what El Niño delivers.
Potholes can pop up quickly when moisture seeps into and below asphalt, ADOT noted, and the road surface can be stressed by the combination of freezing overnight temperatures and daytime thawing. “Add traffic, and that pavement can break away,” it said.
ADOT said the Flagstaff area usually experiences more than 200 daily freeze-thaw cycles each year, creating a challenge for ADOT maintenance crews in that region who have been with pothole repairs since a weeklong series of storms swept across the state in early January.
But it said that even in the state’s warmer regions, where freezing doesn’t occur as often, pothole repair comes with the territory after storms roll through. Amid predictions of a wetter-than-normal winter, ADOT said its crews will probably see more potholes develop.
“Our work doesn’t stop when the snowplows are put away,” said Brent Cain, the ADOT assistant director in charge of the Transportation Systems Management and Operations Division. “Our crews put in long hours to keep the pavement as smooth as possible. It’s a real challenge to keep up with Mother Nature and heavy traffic.”
When storms create potholes, highway workers make initial temporary repairs as soon as possible with patches made from a product called “universal paving material,” which is heated, placed in the damaged area and tamped down.
More permanent repairs come after the pavement has had time to dry out. That involves using a milling machine to remove a section of pavement around the pothole. A sticky oil is sprayed into the milled area being fixed before the recycled asphalt is placed on top. Crews finish by using a heavy compaction roller to smooth out the pavement.
The annual cost of pothole and other pavement repairs depends on the severity of a winter season. ADOT usually plans on spending about 10 percent of its winter operations budget on pothole repair.