Better Winter Maintenance Management

Key highlights from the Sixth International Symposium on Snow Removal and Ice Control Technology keep you up-to-date.

by Ruth W. Stidger, Editor-in-Chief

In June, this important winter maintenance symposium was held in Spokane, Washington.

The Transportation Research Board Committee on Winter Maintenance, along with the Washington State Department of Transportation, the American Association of State Highway and Transportation Officials, and the Federal Highway Administration sponsored the meeting.

Weather information

One area of software covered at the conference was that developed in the Winter Road Maintenance Decision Support System Project.

Familiar names — Paul Pisano, FHWA; Andrew Stern, Mitretek Systems; William Mahoney and William Meyers, National Association for Atmospheric Research; and Dennis Berkheimer, Iowa Department of Transportation — were involved in summing up results of the project.

Now at a prototype stage, the MDSS underwent a second round of field demonstrations last winter.

Iowa field tests used program modules to forecast weather and road conditions and then applied computerized criteria to that data to determine the best road treatments, including:

• Timing of initial and subsequent treatments.

• Type of treatments.

• Amounts of chemicals, when chosen as a treatment.

A line display screen shows weather and road conditions and alerts, products and/or treatments to use, and treatment timing.

A separate treatment selector screen gives current chemical concentration and additional treatments if needed.

Earlier demos, also in Iowa, used the system on 15 routes and in three state DOT maintenance garages.

How well did the system work? “A February, 2003 snow storm provided the heaviest snowstorm of the demonstration with nearly a foot of snow deposited over the region,” the project report states. “In Des Moines, the event started as rain, and then changed to snow that lasted almost 20 hours.

“The MDSS recommended a pretreatment of liquid brine several hours before the onset of the precipitation because the MDSS forecast called for a period of freezing rain, which did not materialize. The Des Moines West garage did not perform a pretreatment since they recognized that the initial period of rain would have reduced the effectiveness of the brine.

“The MDSS then recommended 12 chemical treatments ranging from 100 to 350 pounds per lane mile. The overall treatment recommendation was about twice the tonnage actually applied by the garage. However, it did supplement its treatments with plow-only operations.

“As a result of the case studies, many algorithms within the rules of practice modules were updated with information collected during the demonstration.”

Software and documentation from the project are available — including a third version — from the National Center for Atmospheric Research.

Another study involving computer models focused on the national Cooperative Highway Research Program’s multi-year efforts outlined by Consultant Robert Blackburn, AFM Engineering Services’ Duane Amsler, Sr., and the Midwest Research Institute’s Karin Bauer.

The study helped determine materials and methods strategies and tactics for various climates, road types, traffic conditions, and so on.

Agencies set levels-of-service goals both during a winter event and after the end of the storm.

High LOS measures were targeted for heavy-traffic or essential-route roads.

Snow and ice control strategies were categorized as:

• Anti-icing.

• Deicing.

• Mechanical removal of snow and ice together with traction enhancement.

• Traction enhancement.

• Combinations of strategies.

Originally the research looked at 10 combinations of strategies and treatments. Five of the 20 were used in field evaluations over three winters:

1. Anti-icing strategy with appropriate chemical form, such as solids, prewetted solids, and possibly liquids on lower-volume primary highways and local roads, followed by a subsequent strategy of mechanical removal of snow and ice together with friction enhancement if necessary.

2. Anti-icing strategy of appropriate chemical forms, including solids, prewetted solids, and liquids at selected highway locations such as hills, curves, intersections, grades, or selected bridge decks.

3. Anti-icing or deicing strategy with appropriate chemical forms on lower-volume primary highways and local road systems.

4. Anti-icing strategy with liquid chemical application on bridge decks to prevent preferential icing.

5. Mechanical snow and ice removal strategy with abrasives prewetted with liquid chemicals.

Dilution potential — low, medium, or high — was also considered.

Maintenance programs

Not surprisingly, the Iowa Department of Transportation’s Leland Smith presented ideas for a Proactive Snow and Ice Control Toolbox at the symposium.

Smith, always at the forefront of research made practical, cited various national costs related to roads and bad weather:

• 7,000 fatalities per year.

• 800,000 injuries per year.

• $42 billion in costs per year.

Current spending to deal with bad weather includes $2 billion a year spent by state and local government on snow and ice control and $5 billion a year for infrastructure repairs because of snow- and ice-control damage.

Better training is needed, Smith says, to give snow- and ice-control managers and supervisors more understanding of how to work cooperatively with each other and with weather data provided.

They need to learn snow- and ice-control strategies and when to use them.

Smith focused on FORETELL, software to collect, forecast, and distribute specific road weather data including:

Detailed weather forecasts generated four times each day and 24 hours into the future.

Data provided at 10-kilometer gridded resolution, increasing the ability to pinpoint which areas are being affected by winter weather conditions.

Grid atmospheric weather forecasts and nowcasts mapped to Interstates and U.S. and state highways to predict pavement conditions.

Gathered and translated atmospheric and road-condition information from specific road points to generate easily understood descriptions of the road and weather conditions.

Road and weather event descriptions distributed on demand with fax, pager, and e-mail notification.

You can see a video demonstration of FORETELL at itspubs@fhwa.dot.gov.

Another tool Smith likes is an improved type of snowplow. Called a Highway Maintenance Concept Vehicle, the truck was developed over a seven-year period beginning with 600 ideas combined into 181 desired capabilities.

Three prototype concept vehicles were built, including air and pavement temperature sensors, global positioning systems, real-time data communications, an engine power booster, liquid chemical-applying equipment, dry-spreading equipment, back-up sensors, and a pavement friction device.

Later, a mobile chemical sensor was added.

Automated systems let the operator drive the truck and the winter-maintenance supervisor monitor conditions for the snowplow fleet.

The Indiana Department of Transportation’s Winter Severity Index was discussed at the symposium by Bob McCulloch, Purdue University; and the DOT’s Dennis Belter, Tom Konieczny, and Tony McClellan.

The department researchers began by studying other states’ indexes.

Indiana weather data from four regions and field operations input provided a starting point for the Indiana equation. The original form was:

Weather Index = a (frost day) + b (freezing rain) + c (snow event) + d (drift day).

Checking the equation with real events provided material to analyze and evaluate.

After analysis, separate equations were created for each geographic region. Once this was done, the equations and winter-maintenance costs per mile correlated well.

The index can be used to verify snow and ice removal costs, to check the cost effectiveness of new technology, and to better allocate funds where most needed.

Several presentations from other countries’ road agencies provided good information. One of the best was the Danish Road Directorate’s Freddy Knudsen’s look at winter service quality improvement.

Focusing on computerization and software, their online data collection of equipment use, performance, and results were of special interest.

The system includes salt spreaders, plows, and sweepers. It shows operators’ work quality as well as equipment efficiencies. The system:

Handles all administrative information about contractors, drivers, phone numbers, routes, equipment, contracts, duty rosters, and so on.

Helps the operator during a call-out for salting and snow clearing. It is supposed to facilitate an easy and safe call-out and still ensure registration of all necessary events.

Documents every decision and action on the winter central.

Is the basis for various reports and statistics on the winter season.

Ensure the distribution of information about the road conditions to police, rescue, services, the traffic information center, radios, and the Internet.

Global positioning systems added to the program mean more precise control of spreading. Operators can override the GPS salt-spreading adjustments in windy or other conditions.

The environment

Many winter-maintenance environmental issues revolve around the use of salt in deicing. Washington State DOT’s Enrico Baroga focused on a departmental pilot salt project at the symposium.

The program compared the use of sodium chloride and corrosion-inhibited chemicals.

Up-front costs were significantly less for salt use, as expected, Baroga says. Deicing results were similar for both materials.

Washington DOT specs call for corrosion-inhibited materials to be at least 70% less corrosive than salt.

None of the materials studied met that spec in any comparison scenario, according to Baroga.

Bridge deicing

Bridge surfaces freeze first and this was an important topic for the symposium. Christopher Tuan, University of Nebraska-Lincoln, and Sherif Yehia, Western Michigan University looked at use of conductive concrete overlay on a deck at Roca, Nebraska.

The concrete is a cementitious admixture containing electrically conductive components. These attain stable and high electrical conductivity, creating enough heat to prevent ice formation when the deck is connected to a power source.

Yehia and Tuan developed the conductive concrete mix used in the 3.5-inch-thick Roca Bridge deck overlay.

Two slabs were preheated from two to 10 hours before the storm, depending on temperature expected. In other tests, the slabs were heated during the storms.

Average cost of heating the overlays was $0.08 per kilowatt hour.

Another way to deal with freezing bridge structures provided a topic for Surface Systems-Quixote’s Jerry Waldman. Automatic anti-icer spraying does the trick when a Road Weather Information System warns that a freeze is imminent.

Large-volume control

Areas with lots of snow need special ways to corral it. Snow fences can help.

Now, there is the blower snow fence, which was developed in Japan by the Civil Engineering Research Institute of Hokkaido, the Sekisui Jushi Corporation, and Sanei Kogyo Company, Limited.

Masaru Matsuzawa, Yasuhiko Ito, and Yasuhiko Kajiya prepared symposium materials for the CERTI, while Shinya Fujiwara represented Sekisui Jushi and Masayuki Murakami represented Sanei Kogyo.

The blower fence uses lateral fins attached obliquely to vertical supports. This redirects wind downward, which blows snow away from the road.

With oblique winds, modified fins use wind straightening vanes. This change made the modified blower fence 10% more effective.

In the western United States, snow sails were used to form an avalanche-starting zone defense system on U.S. 89/191. Details were presented by Rand Decker, Northern Arizona University; Robert Rice, University of California-Merced; and Ted Wells and Jamie Yount, Wyoming DOT.

Snow sails were developed in Europe and are only used in areas where wind-slab avalanches may occur. Sails must be positioned so that the distance between them is 1 to 1.5 times the top width of the sail.

Costs to make, move, and install 50 snow sails, plus making a reserve of 10 additional sails, reached about $90,000 according to the Wyoming DOT.

Annual removal and replacements costs run an estimated $21,000.

The test use showed that the sails redistributed snow packs and led to elongated regions of increased density. This inhibits the development of wind slabs and the potential for wind-slab avalanches at the site.

(Graphs from article are at end of article)

Graphs from Article:

Reprinted from Better Roads Magazine
October 2004

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