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The Call and Report Module feeds operations data
such as route, method, start and stop times, material used, and so on,
tying into a Geographical Information System map. Economic follow-up
measures the costs in ways you specify. For more information go to
www.enera.com/wrms/
.
Measuring performance
In Alberta, Canada, Alberta Transportation has
implemented performance-based planning and monitoring of the province’s
highway network. Lynne Cowe Falls, Roy Jurgens, and Jack Chan presented
details at the 2006 Transportation Research Board meeting in a report.
The program is part of a move into asset
management.
Performances measured include safety, mobility,
reliability, customer satisfaction, and level of service.
Modeling
In northern Japan, development of a heat balance
model helps determine when to anti-ice roads. Naota Takahashi, Roberto
A. Tokunaga, Motoki Asano, and Nobuyoshi Ishikawa with the Civil
Engineering Research Institute of Hokkaito and the Institute of Low
Temperature Science gave details at the 2006 TRB meeting. The
heat-balance model measures heat transfer at the road surface and
projects the data to predict when anti-icing materials need to be used.
On the roads
Colorado uses a multiple-pronged approach to
effective winter maintenance. The Department of Transportation monitors
road conditions using infrared sensors, thermal mapping, and Road
Weather Information Systems. Materials are chosen and applied after
maintenance workers evaluate air temperature, humidity levels, dew point
temperatures, exposure to solar radiation, type and rate of
precipitation, weather forecasts, satellite data, and weather radar
data.
Sand and sand/salt mixtures are used to increase
traction on ice. Liquid anti-icers and deicers use mineral salt
compounds such as magnesium chloride to lower the freezing point of
moisture on the roads.
New, larger trucks let CDOT cover up to 38 feet
of roadway (two road lanes plus two highway shoulders) in one pass when
spraying.
Liquid treatments have less negative impact on
bridge decks, vegetation, and water supplies. Better highway safety is
another benefit cited by CDOT.
Anti-icing and prewetting give the maintenance
crew many advantages. Katie O’Keefe and Xianming Shi, Western
Transportation Institute, reported a study with the Pacific Northwest
Snowfighters Association at the 2006 TRB meeting.
The study found that failure to get snowplows
out and salt on the roads during a single day of winter storm costs
almost three times more in lost wages than the total annual costs for
snowfighting.
For the public, O’Keefe and Shi say, all
maintenance activities decrease the potential for accidents and increase
the ability to travel. Improved maintenance strategies have lowered
accident rates even further. Colorado has seen a 14% decrease in snow-
and ice-related crashes during a 12-year study involving advanced
maintenance strategies on the Interstate system in the Denver area.
The United States spends more than $2.3 billion
annually on snow and ice control operations. Colorado, Idaho, Montana,
Oregon, and Washington are part of the PNS association and make up 5% of this expense at
about $114 million.
Traditionally, winter maintenance was heavily
reliant on plowing, sanding, and deicing. Through research, we see that
these methods are still heavily used.
In 15 states surveyed, plowing was used 92% of
the time. Sanding was used 75% of the time. Deicing was used 76% of the
time. Anti-icing was used only 29% of the time.
Anti-icing and prewetting are maintenance
methods that are improving the ways agencies manage winter road
problems, O’Keefe and Shi report. The majority of agencies from both PNS
and non-PNS states have had five to 10 years of experience with
prewetting. About half of the PNS states had more than 10 years
experience with anti-icing, but none of the non-PNS states fell into
this category.
Both anti-icing and prewetting are efficient
means of winter maintenance and have been found to decrease maintenance
costs while reducing the vulnerability of the highway system in winter
weather.
For more data, e-mail
kbokeefe@gmail.com.
Colorado uses a multiple-pronged approach to effective winter maintenance.
Material choice
Some answers to the age-old question of which
materials give the most effective protection were determined in a
Canadian survey using data collected from a large-scale field test
involving measurements on snow cover, weather and pavement conditions,
and treatment operations at 10-minute intervals over 16 snow storms.
Liping Fu, Rudolph Sooklall, and Max S.
Perchanok presented study results at the 2006 TRB meeting.
The data were collected at the DART field site
by MTO forces, Fu, Sooklall, and Perchanok say. The test site is a
50-kilometer maintenance route on Highway 21 located in the Great
Lakes-St. Lawrence area in Ontario. The route has frequent lake-effect
snowfalls and normal winter accumulation of 2.8 meters over 75 to 80
snowfall days.
Highway 21 is a Service Class 2 highway with
winter average daily traffic from 2,000 to 6,000 vehicles. This requires
plowing when snow reaches 20 mm and recovery of bare pavement within
eight hours after a storm.
The 50-km test route was divided into eight
sections, all paved with asphalt concrete.
Different chemical application protocols,
varying by material type, application rate, and application method, were
tested. Prewetted chemicals included near-saturation solutions of sodium
chloride brine, calcium chloride brine with corrosion-inhibiting
additives, and magnesium chloride brine with inhibiting additives.
Results of the study showed that prewetted salt
outperformed dry salt in most test cases, reducing snow cover from 17.9
to 40%.
As a prewetting agent, calcium chloride was much
more effective than magnesium chloride brine, regardless of the dry salt
rate or prewetting rate. Calcium chloride outperformed by 9.5 to 71.4%
in terms of reduction of average snow cover. Calcium chloride brine was
also more effective than salt brine.
Snow removal was not successful under high wind
speeds due to blowing snow. The cumulative amount of salt and sand/salt
mix applied had a positive effect on snow removal.
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