Record snowfall has covered the U.K., while cold temperatures are gripping Europe. Seoul and Beijing have seen their heaviest snowfalls in recent memory, and arctic temperatures have penetrated the U.S. far enough to threaten crops in Florida. For those who have to commute to work in such weather, this is a good time to appreciate the technology incorporated into winter service vehicles.
Sand- and salt trucks have evolved a long way from the era when two men with shovels used to stand on the back of a dump truck. Modern grit is a mixture of sand and rock salt, but the latter has deleterious effects not only on metal vehicle frames, but also on vegetation and freshwater lakes and streams. A variety of techniques have therefore been devised to keep roads on a "low-salt diet."
"Pre-wetting" the salt -- spraying it with brine as it's dropped -- helps it stick to the road better, meaning crews can cut back from 500 pounds per mile to 200...
Vehicle-mounted electronic thermometers let supervisors know how far above or below freezing the pavement is. Some truck cabs have up-to-the-minute weather radar so crews know how long it'll be before the freezing rain or snow hits...
To prevent the grit from being thrown off the road surface by vehicle tires, additional substances may be intermixed to increase adherence. The earliest additive was molasses, but it was difficult to use in cold weather and tended to attract cows and wildlife to the roads.
That means using brine, magnesium chloride and a sugar beet byproduct, which are mixed via a dozen yellow-handled valves marked with letters of the alphabet.
Fine-tuning the grit application to the weather conditions not only saves taxpayers money (one truckload of salt costs ~$800), but also reduces chloride levels in nearby lakes.http://www.startribune.com/local/south/80513267.html. Photo credit Richard Tsong Taatarii, Star Tribune