Snow/ice removal consists of plowing snow and ice from bridges, roadways, and shoulders.
Sanding activities place abrasives on road and bridge surfaces to provide for temporary
traction and safer driving. Temperature suppressant chemicals such as magnesium
chloride (MgCl), are applied as an anti-icer or de-icer, and for pre-wetting of
abrasives, for general winter maintenance. Winter weather and level of service guidelines
help determine rates of application for abrasives and winter chemicals.
Currently about ten million tons of road salt is used each winter in the United States.
A 1994 NCHRP report estimated that North Americans spend $20 billion annually on
snow and ice control. [N]
A more recent report by the New England Transportation Consortium estimated that
winter ice control chemical application in the U.S. alone totaled $500 million per
year, accounting for one-third of highway winter maintenance expenditures in the
United States. [N]
More effective use of deicer chemical could result in significant economical and
While DOTs typically specify and test for heavy metals, pH and nitrogen/nitrates
for all products used for winter maintenance and try to avoid overuse of all materials,
much of managing the environmental effects of winter operations comes down to management
of salt. Salt contamination has become a growing issue for some state DOTs, which
have had to purchase contaminated wells and properties and have had to extend pipes
to municipal water systems. In Canada, salt has become more heavily regulated by
the federal environmental agency; the Canadian Ministers of the Environment and
of Health therefore recommended adding road salts to Schedule 1 of Canada's Environmental
Protection Act of 1999. In response, Environment Canada proposed management measures
to minimize the impacts of road salt on the environment in late 2003. [N]
The Transportation Association of Canada and many DOTs in the United States have
begun to develop best practices to minimize salt usage and salt entry into the environment
surrounding roads and maintenance facilities. Along with reduced salt usage and
the shift to more proactive anti-icing methods, sand usage, water and air quality
problems, and roadside vegetation inundation decrease as well. The stewardship practices
are compiled to help transportation agencies implement a winter operations program
with reduced impacts to the environment from salt, sand, and other chemicals.
The transition to reduced salt usage has been facilitated by great improvements in
snowfighting equipment and technology in recent years. Equipment is available to
facilitate precise, controlled applications of material, at reduced rates established
as a result of extensive research and testing. While much of this new equipment
is more sophisticated, durable, and easier to use, the potential benefits can be
best realized if maintenance staff are thoroughly trained, material use is closely
monitored, and feedback systems are in place. Increasingly, application rates are
being tied into sensor based information systems including real time data, weather
forecasts, road friction measurements, road surface temperature measurements, and
global positioning equipment. As the use of this technology evolves, considerable
planning, organization, and evaluation are required to ensure the best use of existing
Some DOTs are also taking a closer look at sensitive areas, for special consideration
and/or altered practices. Such areas include: [N]
- Spawning streams and those inhabited by federally protected or state listed
sensitive aquatic species, especially trout and other listed or candidate fish.
- Those impaired water segments listed on the state's "Section 303(d) List"
for Total Maximum Daily Load (TMDL) Plan development and restoration.
- Those receiving direct runoff from treated roads and highways where there would
be less than 100:1 dilution;
- Those where a large volume of highway runoff can directly reach small, poorly
flushed ponds, lakes and wetlands.
- Those where receiving water temperatures have warmed by the time highway runoff
This chapter on environmental stewardship practices in winter operations will first
identify recommended practices for strategic planning for reduced salt usage, and
then look at initiatives by leading DOTs, and practices and accomplishments in specific
program areas to achieve such reductions and improve environmental outcomes.