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Dallas, Birmingham, and Augusta are some of the
cities that seldom face major winter storms. Still, residents dread the
forecast of ice.
Agencies with only occasional winter weather to
battle don’t arm themselves with fleets and plows. And in Dallas,
deicing and anti-icing are words only used in the Better Roads’
editorial office.
A desultory toss of sand on some bridge
approaches, at a few critical intersections and a very few inclines,
seems to be the rule of the day in most occasional-ice cities.
The new method
A new technique uses a mix of hot water and
sand, according to Torgeir Vaa, Sintef Roads and Transport in Norway.
Sand quality is a critical element, as are the
amount and temperature of the water and the spreading speed.
Sand should be 0- to 0.16-inch gradation. Water
should be from 194 to 203 degrees F. Water should make up about 30% of
the total material weight or about 6 ounces per square yard.
Once placed, the sanding lasts longer than
conventional sanding, Vaa says. Adequate friction levels last up to a
week on streets with traffic of up to 700 vehicles per day and from
three to seven days on streets with 1,500 average daily traffic.
Truck adaption
 Trucks
are adapted for the method by mounting a 90-cubic-foot water-holding
tank and a heater with a water pump. The two systems are separated to
allow sand spreading without water when necessary.
Sand is sprinkled with the hot water as it
leaves the spinner-type spreader. As the material hits the street, it
freezes in small lumps giving the pavement surface a sandpaper-like
quality.
Effectiveness
Use of hot-water sanding works well with
occasional ice storms — and has a good effect on street icing problems
usually difficult to treat, Vaa says. These include:
In usual icing conditions, effects of the
warm-wetted sand lasted 10 to 20 times longer than dry sand.
This degree of effectiveness reduces the need
for repeated sanding. Indeed, in most occasional ice-storm locations,
the ice will melt by the time effectiveness is lost.
Look ahead
 Vaa
says use of warm-wetted sanding continues to expand. His agency is also
trying hot-water prewetting of salt to speed its chemical processes.
Some spreaders have been fitted with automatic
data recording based on global positioning systems.
One truck uses a mounted friction measurement
device to give continuous readings.
Will warm-water sanding work in the United
States? It’s worth a try. And more acceptable to drivers than today’s
usual radio-broadcast warning, “Stay home till the ice melts.”
Reprinted from Better Roads Magazine
October 2004 |
