1/24/2008
Plowing, sanding, deicing not foolproof
RIGBY - While maintenance crews have and will continue to work hard to keep state highways traversable in severe winter conditions, no amount of plowing, sanding and deicing can make slick roads perfectly safe, the Idaho Transportation Department (ITD) cautioned.
Even after plowing, sanding and deicing, roads can retain a thin layer of ice, which can be extremely slick, or become wet, reducing traction and increasing the chance for hydroplaning.
In subzero temperatures, water used to apply magnesium chloride deicer (or anti-icer) can freeze, causing sheets of ice on the highway. Given the frigid weather of eastern Idaho, this chemical has limited use in District 6.
The best all-around remedy for motorists is to slow down - way down.
District 6 Engineer Tom Cole said snowplows remove all the snow and ice possible, but residue remains on the road, which can be slippery.
Sanding improves traction, Cole said, but surfaces may still be slick, especially as salt in the sand begins to melt snow and ice.
Maintenance crews in eastern Idaho work around the clock when needed. Crews on U.S. 20 north of Ashton actually work 8 hour shifts 24 hours a day seven days a week all winter long. During storms, the Ashton area foreman brings in additional drivers as needed.
At maintenance sheds in Idaho Falls and Rigby, a technician checks all regional highways at 1 a.m. and then calls in crews for 10-hour shifts if necessary.
"When we say 'Slow down,' we don't mean easing from 65 to 55," Cole said. "We mean dropping to 25 or 30, perhaps slower."
Cole said District 6 sometimes uses calcium chloride coupled with salt, sand and cinder to soften up a snow floor. But if the wind is blowing, this combination is of little use, since the ingredients will be carried off the road and wasted.
Another reason the district avoids applying calcium chloride or salt to highways if the wind is blowing is that chemicals melt the snow as it moves across the road, causing ice to build up even quicker on the travelway.
Under severe conditions, the district sometimes closes roads. "Not only can highways themselves be treacherous due to super-slick surfaces or low visibility," Cole said, "but one inexperienced driver in a snowstorm poses a threat to everyone on the road.
"Travel is dangerous under the best of conditions," Cole noted. "There may be obstacles on the road, uneven surfaces, reckless drivers . . . any number of things. Drivers must always be attentive."
For current information on highway and weather conditions, dial 5-1-1 or visit 511.idaho.gov, which are ITD's telephone and Internet traveler information services.