BOUNTIFUL — Surprise! It's the inversion.
Persistent road problems are continuing, and they're being blamed in part on the smoggy, foggy, very cold, bad air — which has regularly left a thin, icy layer for drivers to overlook.
"With the inversion, with as cold as temperatures have been recently, any kind of moisture is going to bond to the road surface and really create some hazardous conditions," said John Gleason, spokesman for the Utah Department of Transportation.
More problems were seen early Tuesday on I-15 in Bountiful near 500 West, where icy roads left behind by moisture from the fog were the stage for two separate crashes.
Those accidents came after a deadly rollover Saturday which killed three people, including a former KSL employee. Investigators said slick roads contributed to that crash.
Gleason said UDOT has had to be extra vigilant about road conditions this year because the usual tricks aren't working as well with the recent extreme cold.
"When it gets below 20 degrees, salt becomes less effective," Gleason said.
KSL News rode along with a Utah Highway Patrol trooper Tuesday afternoon to get a handle on why road conditions have been frequently deceiving for drivers. Sometimes the roads didn't have that glazed look but were still slick.
"You'll have patches of fluid and water that are still on the ground. You've also got the loose salt," observed UHP Trooper Nolan Kerr as he headed north on I-15.
Even wet roads, he said, can prove to be too slippery for drivers when other factors come into play — like speed and braking hard.
"So many times I arrive and somebody made the same assumption: ‘It's just a little wet, it shouldn't be too bad,'" Kerr said. "Then their commute just got lengthened by an hour or two."
When there is significant salt residue on a road, the same factors can also lead to crashes. Kerr said driving on a lot of salt residue is like driving on dirt.
Adding to the confusion for drivers, sometimes salt and frost can resemble each other. A pale-looking road, especially in the early morning, more likely means frost than leftover salt, Kerr said.
"It seems like there's just this dusting of white over the road and you're not sure whether it's snow or frost," Kerr said. "Those days have probably been the worst."
Kerr said most problems can be sidestepped by common sense steps like driving slower — even when roads look mostly dry — as well as observing a good following distance and driving with adequate tires.
It's also important not to brake too hard on top of an icy patch, he added, because it's easy to lose control that way.
"Just use your precautions," Kerr said, "even when it doesn't look like it's bad."