Sand and Salt: A Model for Change

A nature of the human condition is to resist change. However, in most cases, change turns out to be a good thing, particularly in the areas of science and technology.

In snow and ice control, one of the most difficult changes for an agency is to change from a policy of abrasives treatment (sand) priority to a policy of chemical treatment (salts and other chemicals) priority.

Truck delivering anti-ice chemicals

Abrasives priority is a policy of using a mixture of abrasives and ice control chemicals, or straight abrasives, to treat snow and ice situations. A chemical priority policy uses straight ice control chemicals, without abrasives, to produce the desired result. The strategy of anti-icing (trying to prevent ice/pavement bond) is inherent in most chemical priority programs.

To transition from an abrasive to a chemical priority policy, examine these steps that have been used successfully by others.

Train, evaluate, and refine

Warren County in New York State and the State of Maine have successfully managed the transition from an abrasives to a chemical priority policy.

Ice control truck driving through a storm

Environmental protection and improved level of service

car encased in ice

Warren County is situated in the Adirondack Mountains. Most of the western watershed of Lake George is in this county. In the early 1990s the loadings of silt and abrasives accumulating in Lake George were generating a high level of environmental concern. The New York State Department of Transportation (NYSDOT) and the Warren County Department of Public Works (DPW) installed many containment features to trap silt and abrasives before they reached Lake George. They also instituted aggressive sweeping programs to pick up abrasives before they entered the drainage system.

In the late 1990s, to further reduce abrasives loadings, the Warren County DPW decided to move from its long-standing abrasives priority policy to a chemical priority policy, and improve their level of snow and ice service. Coincidentally, researchers from the National Cooperative Highway Research Program (NCHRP) contacted Warren County to participate in a field study to compare the cost and performance of a chemical priority policy with those of an abrasives priority policy - A MATCH MADE IN HEAVEN.

Warren County agreed to collect the necessary data. The researchers provided substantial training, experimental design, data collection forms, and data analysis. The results of the three-winter study were compelling. The data showed that an equal or higher level of service could be provided, at less cost, by using a chemical priority approach when compared with an abrasives priority approach. THE DATA SHOWED LESS SALT WOULD BE USED.

Armed with favorable experience, the Warren County DPW has fully implemented the chemical priority policy. Brian Humphrey, [then] Highway Operations Manager for the DPW, facilitated the research work and implemented the results. Brian felt that by pre-wetting solid sodium chloride (salt) with a liquid magnesium chloride product that contains an organic ice control chemical the implementation was easier for the customers and the maintenance workers. The organic chemical colors the salt and made it visible to motorists and the DPW personnel.

Average Cost per Storm (Snow and Ice Event)
– Warren County, NY

 

Salt First Policy

Abrasive First Policy (with 7% Salt Mix)

Sand Used (tons/lane-mile)

0.2

1.1

Salt Used (tons/lane-mile)

0.5

0.5

Number of trips
per event (average)

5.0

6.7

Total Cost
(Materials only) per Event

$82

$152

Cost ratio (Sand$/Salt$)

 

1.85

Notes: Assumes similar level of service
Costs are $7 / ton for sand and $30 per ton for salt.
7 % salt needed to keep sand from freezing in the pile or while using.
Some sand is still used with a salt first policy in storms where salt is not effective

Warren County accomplished their objectives by having a clear understanding of what they wanted to accomplish, gathering good data that supported their position, and implementing the policy change over a period of several years.

Anti-icing cuts cost and increases level of service

pickup with liquid ice control spreading equipment
Liquid ice control
spreading equipment

In the mid-1990s, the State of Maine Department of Transportation (MEDOT) was tracking the Strategic Highway Research Program (SHRP) and the Federal Highway Administration’s (FHWA) strategy of anti-icing. MEDOT’s long-standing practice of using an abrasives priority policy with 7 percent chemical (salt) was not compatible with anti-icing. As a result, MEDOT requested training in anti-icing and a chemical priority policy from the FHWA’s Ice Warrior Program.

In the year following the training, MEDOT, like Warren County, was contacted by researchers from NCHRP to participate in a comparison study of chemical and abrasives priority policies. They agreed. Another MATCH MADE IN HEAVEN.

There were a number of test sections in a variety of settings. The test results were similar to those experienced by Warren County DPW. The comparative cost of materials use ranged from break even in one location, to the chemical priority sections being cheaper by a factor of three in others. In the area where the materials cost was about equal, there was a much higher level of service (better road conditions) observed in the chemical priority section. In the other areas, the observed level of service in the chemical priority sections was equal to, or slightly better than, the level of service observed in the abrasives priority sections. The table on page 4 shows the average results from Warren County. The material costs alone are 1.85 times as much for an abrasives first policy even with lower salt costs when the study was done.

Truck with liquid ice control equipment

The test results were compelling enough to convince upper management at MEDOT that anti-icing and a chemical priority policy were the way to go. Implementation is progressing satisfactorily. Steve Hunneywell, Assistant Highway Maintenance Engineer for MEDOT said that accrued savings from the changeover were invested in additional anti-icing capability. A huge training investment in anti-icing and a chemical priority policy is being undertaken. Their WISE (Winter Ice and Snow Experts) College is patterned after the Snow College of the NYSDOT. Large numbers of maintenance workers are exposed to intensive training in snow and ice control equipment, materials, and methods.

MEDOT now has the capability to pre-treat (applying ice control chemicals to the pavement before an event) its highest priority highways with salt brine. They feel this will provide an even higher level of service.

The Maine DOT accomplished their objectives by monitoring what was happening in snow and ice control technology, obtaining training support from the FHWA and peer states, gathering data that supported their theories, and implementing their policies through intensive and recurring training.
In short, a chemical priority policy can save money. It can also improve services and reduce pollution. If you are considering making a change, talk to your colleagues, or call the Cornell Local Roads Program. Try something new. Remember, if you do what you have always done, you will get what you have always gotten.

Truck with liquid ice control equipment

Commonly Used Snow and Ice Control Chemicals

Material

Notes

Effective to a, b (temp in °F)

Cost per Ton (2014)c

Sodium chloride (rock salt)

Most widely used chemical for snow and ice control.

15°F

$20-30

Calcium chloride

More corrosion potential than rock salt, but is effective at lower temperatures.

-20°F

Flake $440-575

Magnesium chloride

Less commonly used, but effective chloride with somewhat less corrosive potential.

0°F

$100-180

Urea

Used at airports due to low corrosion potential. Not as effective in melting snow as chlorides.

24°F

~$320

Calcium magnesium acetate (CMA)

Less corrosive synthesized chemical. Not as effective as chlorides.

20°F

>$650

“Carbohydrate enhanced” chemicals

A variety of proprietary products that are usually by–products of organic refining operations usually mixed with chloride chemicals. Provides pre-wetting benefits.

d

d

Sand

Abrasives used to provide temporary friction improvement when chemicals are not effective.e

n.a.

$5-30

a Pavement surface temperature.
b Solid chemical. Liquids have a higher effective temperature.
c Prices vary around New York State due to delivery costs, availability, and demand. Most of the prices are derived from NYSOGS bid prices.
d  Varies in effectiveness and costs (Current NYS Office of General Services (NYSOGS) prices vary from $51-117 per ton as treated salt (which is at least 91.2% Sodium Chloride).
e Typically used when it is too cold for chemicals to work, on low–volume and unpaved roads that have a lower level of service, and, in areas where significant friction is always required to maintain traffic flow (steep hills, etc.).
Amsler, Sr., P.E., Duane (Dewey). Snow and Ice Control 2014. Cornell Local Roads Program No. 13-04

Spring 2014

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This work by the Cornell Local Roads Program (CLRP) is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.