MnDOT sees smoother metro commute this evening
- Blog Post by: Tim Harlow
- December 11, 2012 - 1:23 PM
After two days of white-knuckling, patience-testing commutes for Twin Cities motorists, the drive home Tuesday evening has the potential to be the least aggravating and quickest since Sunday’s substantial snowstorm left a rutty residue on miles and miles of streets and highways.
But a full recovery is not expected until Wednesday. That’s when warmer temperatures and a little bit of sun providing just enough warmth will allow the salt and chemicals applied to the roads to kick in and counter the moisture-laden mix that froze under travelers’ wheels.
"We are out scraping. We are kicking it in the rear and will keep working," said Kent Barnard, spokesman for the Minnesota Department of Transportation (MnDOT). "We hope to see a huge improvement by tonight’s rush hour."
That won’t take much after ice-compacted roads led to many commutes that took up to three times as long as normal and led to scores of crashes and spinouts. At times, traffic was at a standstill on major freeways during Monday’s morning and evening commutes, and repeated Tuesday morning.
The 15 inches of heavy, wet snow melted just enough as it fell to create wet roads, but quickly froze as temperatures plunged into the teens. The remainder of the snow fell on the ice, which was then compacted by motorists who drove over the top of it, allowing it to bond solidly to the pavement, said Mike Kennedy, Minneapolis Public Works superintendent.
"It becomes bulletproof," he said. "We saw this in 1991 with the Halloween snowstorm, and conditions persisted for weeks. This is mini-version of that effect."
Both Minneapolis and the MnDOT applied the typical rock salt and salt brine (a liquid mixture), but those chemicals lose their effectiveness when the temperature falls below 15 degrees.
There are some stronger compounds such as potassium acetate, which MnDOT uses on bridges, or magnesium chloride with soy bean oil that might have had better results. But those with more potency are not always readily available and can harm the environment and infrastructure. They also are more expensive, Kennedy said.
Just how much, "I’m sure quite a bit more," said MnDOT’s Barnard.
Still, motorists might not have minded the additional expense if had given them relief from brutal and gridlock.
City and county roads were bumpy too, and that impacted traffic volumes on the rut-filled roads. That also impacted traffic on highways and freeways, Barnard said.
"People need to understand that our transportation system is inter-connected," he said. "When city streets are bad, they come to our roads."
At times Monday and Tuesday mornings , I-694 from Brooklyn Park to Shoreview resembled a parking lot as drivers skidded into the ditch, and those that didn’t crept along at 15 miles per hour or slower. The rush, or slog hour, persisted well into the morning adding an hour or two to many drivers’ commutes.
At the height of the drive to work, Metro Transit reported that 60 percent of routes were running late with an average of delay of 16 minutes.
Even with all the plows and chemicals that were deployed by MnDOT and county and local municipalities, it looks like Mother Nature will show some mercy by sending temperatures into the 30s on Wednesday and Thursday.
"Absolutely that will be our best friend," Barnard said. "Mother Nature is going to work with us."
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