Relief in sight for heat wave, and why roads buckle
By THE HERALD and LEE NEWSPAPERS
Chippewa Valley residents will have to be content with only two record-setting days during the week-long heat wave.
Thursday’s high of 93 degrees fell short of the forecast high of 99, which would have matched the record for July 5. And today’s projected high of 96 — the eighth consecutive day of 90-degree temps — will not approach the July 6 record.
The excessive heat warning that has been in effect for most of the week continues through 7 p.m. Friday for areas south of a line from New Richmond to Bloomer. Heat index values will be from 102 to 112 degrees in the warning area.
While the heat has caused some people to flock to the outdoor pool in Chippewa Falls, others have chosen to stay put.
Megan Robarge, supervisor of the city’s Recreation Department, said pool usage increased from just over 4,000 in June 2011 to more than 5,500 this past June. And an extra 500 people used the pool this past week compared to a year ago.
“We do have a lot of people who came out this week, but not as many as we would have thought,” Robarge said.
“I think it’s a little too hot. People are trying to stay inside and stay cool,” she said.
Or as Dick Hebert, director of the Parks, Recreation and Forestry Department, put it, “It’s kind of like the winter — they’re hunkering down.”
“And also all of our day cares that usually come down haven’t been coming down,” Robarge said.
A 60 percent chance of thunderstorms Friday night will give way to normal highs in the lower 80s for the next several days.
But until then, expect more of the same. The state Department of Transportation has even gone so far to say that the risk of buckling pavement will be high Friday.
The agency received reports of 17 pavement buckles on major highways on the Fourth of July. Workers were able to make repairs in an average of two to three hours.
Chippewa County has had several cases of pavement buckling that has caused temporary shutdowns of highways and roads, including another Thursday. Which had led several queries as to why roads buckle during hot-weather spells.
It turns out the reason is simple physics: Heat causes materials to expand. When concrete slabs expand beyond the space in the joints they press against each other, causing the surface to buckle at the joint or in a weak spot within the slab.
Rory Rhinesmith, deputy administrator for the DOT’s highway division, said pavement buckling is unpredictable. The type and age of the concrete can be a factor, as is temperature, but the buckles seen this week were “very random,” he said.
There’s no set temperature at which buckles happen, but Rhinesmith said the risk is higher any time it’s hotter than 90. On Thursday, pavement monitors were returning readings as high as 135 degrees.
Because asphalt is more elastic than concrete, it’s less prone to buckling, but Rhinesmith said asphalt will heave when it’s covering an older concrete road bed or under pressure from adjacent concrete.
When buckling occurs in Wisconsin, Rhinesmith said county highway crews will cut or jackhammer away the affected material and put in an asphalt patch to get the road reopened as soon as possible.