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Summer
Maintenance Products
The 1984 Strategic
Transportation Research Study identified pavement maintenance as one of six priority areas
for research and development. As a result, pavement maintenance became one of the key areas in
the Strategic Highway Research Program (SHRP). Established
by Congress in 1987, SHRP’s mission was to increase the durability
and safety of our Nation’s
roads and bridges.
Research conducted under SHRP
targeted six areas: pavement maintenance, concrete and structures,
long-term pavement performance, asphalt, work zone safety, and snow
and ice control. One hundred and thirty products, including new
specifications, tests, equipment, and reports, resulted from SHRP
research contracts, which expired in March 1993.
Pavement
Maintenance
All pavements require
maintenance. They need this attention because stresses producing
minor defects are constantly at work. These stresses may be caused
by such things as traffic loads, temperature fluctuations, and
changes in moisture content. Regardless of the cause, the result is
the same-without timely maintenance the pavement ultimately
deteriorates.
Preventive
maintenance means the early detection and repair of minor defects,
before major corrective action is necessary.
Preventive
maintenance makes sense when one considers that cracks and other
surface breaks, which in their first stages are almost unnoticeable,
may develop into serious defects if not soon repaired. Cracks and
surface breaks may occur in a very few days in an under-designed
pavement under heavy traffic, especially in the presence of water.
For this reason, qualified individuals should perform frequent,
close inspections of the pavement. When these
inspections reveal minor defects they should be repaired
immediately, before they deteriorate into pavement failures
requiring major maintenance expenditures.
Pavement is an investment, as is a building or any other capital
structure. Just as a building must be maintained to ensure its
maximum utility, so must pavement be properly cared-for. Moreover, proper maintenance will
serve to carefully protect and preserve the pavement for the many
years necessary to justify the initial substantial investment.
Winter Maintenance
Products
- More Efficient
Winter Operations
Snow, sleet, and freezing rain can create
treacherous driving conditions. To keep roads clear and safe for
travel, highway agencies spend more than $2 billion every year on
winter maintenance. Conventional winter maintenance operations involve
deicing techniques—that is, sending plows and trucks loaded with
salt and other materials to clear the roadways after a storm has
begun. Although effective, this strategy is costly and labor
intensive, and can cause unnecessary harm to the environment.
Now there is a better way.
The Strategic Highway Research Program (SHRP) found that by switching
from traditional deicing techniques to an anti-icing and pre-wetting strategy coupled
with a road weather information system (RWIS), highway agencies can:
 | Slash winter maintenance costs. |
| Improve travel
conditions (Higher Level of Service). |
| Help protect the environment. |
In
Alaska, an
experimental trial period using a 28 percent magnesium chloride (MgCl) solution
for both anti- and deicing was begun by Alaska DOT (AKDOT) in Valdez, Alaska,
during the winter of 1996-1997. Maintenance and Operations (M&O) purchased
6,000 gallons of MgCl, four 75-gallon saddle tanks for the sanders, and a
2,000-gallon slip-in spray unit for anti-icing. This system allowed AKDOT to
anti-ice prior to a storm event and to de-ice through pre-wetting sand applied
to the snowpack. In 1997-1998, a 32 percent solution was specified.
During 1997-1998, most of the effort centered on the
use of sand pre-wetted. with MgCl. Before and after a storm event, sand was
applied to the roadway and MgCl was sprayed onto the sand as it left the hopper
belt. As the pre-wetted sand hit the snowpack, it melted, diluted, and re-froze,
embedding the sand into the pack. The sand provided immediate, long lasting
friction with very little sand blown into the ditch by traffic. AKDOT experience
found that the chemical continued to work, migrating through the pack over the
next couple of days, turning the pack into a loosely arranged, oatmeal
consistency. This was easily plowed off and some of it sublimated (changed from
a solid to a vapor) as traffic aerated the mixture. This was the first winter
when Valdez experienced mostly ice-free roads. Sand use was reduced by 30
percent. After experimenting with different application rates, AKDOT found 13
gallons per cubic yard optimal for conditions.
The Valdez station conducted anti-icing efforts by
applying about 40 gallons of MgCl per lane mile prior to a storm event. This
program seemed to work well in keeping ice bonds from forming during drier
storms, but had poorer results in storms where it was diluted by rain.
Because of the success of the program, AKDOT has
expanded the use of MgCl to the Cordova and Thompson Pass stations. Two
6,000-gallon storage facilities have been assembled and 5 sanders are now
equipped with pre-wetting systems. Expansion to the colder, interior stations is
under way, especially for use during the fall and spring seasons, when
temperatures are warm.
 
      
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