Featured Article: Intelligent vehicle systems defy bad weather
Better Roads Staff | June 1, 2010
By Tina Grady Barbaccia
The Alaska Department of Transportation and Public Facilities (ADOT&PF) in partnership with the University of Minnesota Intelligent Transportation Systems Institute developed a pilot project using an Intelligent Specialty Vehicle System (ISVS) for winter maintenance vehicles. The ISVS is equipped with Precision Global Positioning System (PGPS) technology known as High Accuracy Differential Global Positioning System (HA-DGPS), which is delivered via Real Time Kinematics (RTK) to the vehicle from a single, dedicated GPS base station.
The vehicle-mounted system has integrated collision avoidance radar technology designed to provide its operator a means to maintain a desired position and avoid collisions with obstacles during periods of low visibility, according to an ADOT&PF “Intelligent Specialty Vehicle System Pilot Program Report” (which is available at http://www.itsdocs.fhwa.dot.gov/JPODOCS/REPTS_TE/14370.htm). The PGPS provides position information to the vehicle, which can be as accurate as 3 cm, according to the ISVS report. In layman’s terms, the system digitally maps the highway. It also digitally maps the location of the centerlines, fog lines, pullouts, and guardrails — any feature on the highway. The system also maps digital airspace so an operator is aware of mountains and other landmarks.
The vehicle-mounted systems were originally installed in two test vehicles: a 1994 Oshkosh snow blower and a 1998 Freightliner 6×6 snowplow. The equipment was eventually installed newer 2006 trucks when the those vehicles were purchased.
“This Heads-Up display [also referred to as a “smartplow”] is the most technologically advanced system we are using,” says Michael J. Coffey, statewide maintenance and operations chief for ADOT&PF. A glass display with the digital map drops down right in front of the snowplow operator on equipment equipped with the system.
“Every feature on the highway is digitally mapped,” Coffey explains. “It’s really amazing. You know where the intersections are, you know where the center dividers are, and even the snow poles, guardrail, and pullouts on highways.”
If an operator starts going too far to the right and crossing over the fog line, [the fog line on the display] starts turning red. If the centerline is crossed, it will turn red. A seat shaker is also tied into the system to help guide operators, he says. “If you cross the fog line, the right side of the seat shakes,” Coffey explains. “If you cross the centerline, the left side shakes. You also get a visual because the line turns red. Another feature that is available, but not currently installed, is an audio where an alarm or horn can go off.”
Additionally, the system has forward-looking radar. This gives the snowplow operator not only a digital map of the roadway in front, but also the radar will depict a little box to represent a car coming toward the operator. “This lets the operator see traffic on the road by the boxes coming and going.”
The agency currently has the technology installed in two pieces of equipment at Thompson Pass and in two pieces at the Deadhorse Airport on the North Slope above the Arctic Circle. At Thompson Pass, about 20 miles outside of Valdez, Alaska, it’s the state’s highest snowfall area in the state. It averages 46 feet of snow per year, but there has been as much as 80 feet, which is equivalent to about a nine-story building.
This is also home to the Richardson Highway, the only road into Valdez and the way to get to the Port of Valdez — where the Alaska pipeline ends — making it a major supply road. “For all these reasons, we needed to do something to keep this road open as much as we could,” Coffey tells Better Roads, “but it’s a challenge because of the high snow, high winds, and whiteout conditions.”
To work on a solution to this problem, ADOT&PF began working with the University of Minnesota’s Intelligent Vehicles Lab. The agency has been so impressed with the system, it is upgrading it and installing another differential base station tower to transmit at lower elevations. Coffey says ADOT&PF is installing equipment in two more vehicles at Thompson Pass and adding the first smart vehicle in Valdez, which will give the agency a total of four smart vehicles at Thompson Pass and one in Valdez.
“Thompson Pass has thousand-foot drop-offs on the side of the road. This keeps operators from worrying about going off the road.”
Michael J. Coffey, statewide maintenance and operations chief for ADOT&PF
“It doesn’t allow us to plow the road faster, but it does enable operators to be out in extreme conditions where we might have to close the road and then we’d be behind,” says Coffey, who will be making a presentation on this technology at the American Association of State Highway and Transportation Officials (AASHTO Annual Meeting in Bismarck, N.D., being held July 11-14. The “smart plow” system also helps operators be more efficient. In whiteout conditions, Coffey says, an operation may roam back and forth along the road. “To get the whole road clear, an operator might have to make multiple passes because [he or she] may not be plowing in a straight line,” he says. “But with this, the guys can keep the plow right on the centerline so they don’t have to come back. It lets us be out on the road more and allows us to do a better of maintaining roads in bad conditions. It also reduces the stress of the operators, making them more comfortable being out in bad conditions. Thompson Pass has thousand-foot drop-offs on the side of the road. This keeps operators from worrying about going off the road.”
Coffey says since the use of a “smartplow” system, ADOT&PF has seen less guardrail damage from winter maintenance. In bad conditions, he says, operators have a tendency to ride guardrails. This flattens the W-beam on the rails, and it can also cause damage to the snowplows. “Instead of flattening miles of rails, operators can now see the guardrails with the heads-up display so it’s reducing damage to them,” Coffey points out.
ADOT&PF is singing the “smartplow’s” praises as being an excellent tool for snowfighters, but because of its cost, “it’s not something you’d use just under normal conditions,” Coffey says. “But under extreme or routinely adverse conditions, it’s a great thing.”
In places such as Wyoming, which doesn’t get 40 feet of snow but often has strong winds, this type of system could be very useful because visibility is compromised when the winds blow snow around, Coffey suggests. “It could be useful even somewhere like coastal California because of the intense fog,” he says.
The Utah Department of Transportation (UDOT) is using front-end truck-mounted brooms to clear light snowfall from roads in Carbon, Emery and Grand County.
A hydraulically-powered horizontal axis broom, which is typically used to sweep excess chips from roads, is successfully being used to sweep away light, fluffy snow from roads in areas that are better known for stark desert and red rocks than snow, explains Lynn Bernhard, P.E., maintenance methods engineer for UDOT. The truck operates at 30 to 35 mph as a combination unit with an anti-icing liquid applicator towed behind, and is dispatched when powdery snow is forecast.
The high mountains to the west of the state bring moisture from snow, making Utah’s snow ideal for skiers who love powder snow, but this type of light, fluffy snow makes it difficult to remove it with conventional plows, says David Babcock, UDOT’s equipment manager in Price. “Brooms throw [the snow] off the road without creating the snow cloud that regular plows create.”
The brooms are mounted on UDOT standard snowplow mounting brackets. They can be quickly exchanged for traditional plows if necessary, Bernhard explains. Because powder snow doesn’t typically turn into heavy wet snow during a storm, plow changes are few and far between, Bernhard says. “Applying salt brine early in the storm prevents packed snow bonding to sub-freezing pavements,” he says. “The trailer-mounted anti-icing unit can be disconnected and parked as operations shift from initial storm attack to repetitive plowing as the storm progresses.”
Contract Weather Forecasting
Use of a contract weather forecast service — in this case Northwest WeatherNet Inc. — to provide advance road weather forecasts throughout Utah provide pre-storm forecasts that include probable snow type and possible changes during the storm. This enables agency equipment operators to prepare for the storm or weather incident with specific equipment types — such as determining whether to use a plow, broom, or a combination of attachments.
Forecasters are located at the UDOT Traffic Operations Center (TOC) in Salt Lake City and provide detailed road weather forecasts for all state roads from Saint George in Utah’s desert southwest corner to 11,000-foot summits in the Rocky Mountains, says Lynn Bernhard, P.E., maintenance methods engineer for the Utah Department of Transportation (UDOT).
“Feedback from plow drivers has sharpened the forecasters’ skills to predict weather in areas affected by distinct microclimates and mountain-induced unusual weather patterns,” Bernhard explains. “Using truck-mounted brooms for fighting snow is a local adaptation that has proven it’s worth it in this unique desert region.”
Tunneling Through Super-Cooled Fog
In northern Utah, super-cooled fog — less than 32 degrees Fahrenheit — can stay in the mountain valleys for weeks. Based on recommendations in a field trial report (the report is available at http://www.fhwa.dot.gov/weather/best_practices/CaseStudies/025.pdf) and lessons learned from anti-icing operations near Salt Lake International Airport, maintenance personnel configured a truck with fog dispersal equipment composed of commercial, off-the-shelf products. Going to this configuration was more cost-effective than the customized configuration developed by the Department of Meteorology at the University of Utah, which was prohibitively expensive, according to the report, “Best Practices for Road Weather Management, Version 2.0.”
Prior to the deployment of fog dispersal equipment in 2000, the DOT had developed a two-hour training course to ensure employee safety when working with compressed liquid carbon dioxide, including oxygen-displacement properties of the chemical, chemical handling techniques, and operation of the high-pressure dispenser.
Fog dispersal equipment is composed of commercially available products and is installed on about 70 maintenance vehicles for UDOT — about 15 percent of the fleet. Each truck is equipped with a compressed gas cylinder, a manual valve assembly mounting brackets, copper pipe and a dispensing nozzle. Each cylinder holds liquid carbon dioxide at a pressure of 2,000 pounds per square inch.
Nozzles are placed on top of a plow truck, explains Bill Hoffman, chief maintenance and operations engineer for the Nevada Department of Transportation. As the truck is driving its normal speed, the liquid carbon dioxide is dispersed up into the slipstream of the truck.
“The liquid CO2 crystallizes fog vapor particles so they drop out and are too heavy to stay in the air,” Hoffman says. “It creates a ‘tunnel.’” However, this doesn’t work if it rains or if there is fog that is too warm. Hoffman says it has to be done during the winter, “and the condition has to be pretty exact.”
The cost of magnesium chloride and potassium acetate has steady been rising so agencies have been looking to find an alternative or replacement. In Alaska, there is the added expense of everything needing to be shipped. ADOT&PF went the homemade route and began making its own brine in Sitka, Valdez and Juneau, Alaska. Next summer, the agency plans to install a salt brining unit in Fairbanks.
The significance? The Fairbanks area has never done anti-icing before. “It’s the interior part of Alaska, and in times past, summers have been 90 degrees [Fahrenheit], followed by two to three weeks of fall, and then by Oct. 1 temps fall to below zero and stay that way until April,” explains Michael J. Coffey, statewide maintenance and operations chief for the Alaska Department of Transportation and Public Facilities. It’s not uncommon for Fairbanks, to deal with temperatures 50 degrees below zero, he says. But during the past several years, the area has been getting more freeze-thaw cycles in the fall and spring. That means the transition from fall to winter used to be two to three weeks — possibly a month. Now that timeframe is six to seven weeks and includes freezing rain events. “That means we now have to do things differently,” Coffey notes. “We’ve done things differently by applying salt brine with a corrosion inhibitor, and it’s been a significant money saver.”
For more on homemade brine and an innovative salt slurry generator that’s used with it, see the June 2009 print edition of Better Roads and the December 2009 print edition for our Top 20 Products of 2009 (or go to http://www.betterroads.com/featured-article-the-2009-top-rollouts), in which this slurry spreader that uses homemade brine was featured.
Push a Plow, Pull a Plow
A very long trailer with a snowplow on it — i.e. a “tow plow” is enabling agencies to clear 2 to 2-1/2 lanes with just one operator. Before this equipment configuration was developed, the same job would have taken two passes and two people, says Bill Hoffman, chief maintenance and operations engineer for the Nevada Department of Transportation. Now one person can do the job by plowing in front with a traditional plow and in the back with a trailer, or “tow plow,” he says.
The equipment configuration isn’t brand new. The Missouri Department of Transportation (MoDOT) has been using it for two to three years (which is why the tow plow was originally dubbed the “Missouri Snow Plow”). But now it has moved beyond the Missouri borders and is being adopted by other agencies.
“It’s almost scary to see pictures of this plow truck with a trailer,” Hoffman says. “It looks extremely dangerous. But I’d love to get my hands on a few of these. I think the tow plow is an efficient use of taxpayer dollars because it will pay for itself in one winter.”
In fact, use of the tow plows could increase safety and provide cost savings for an agency because operators are on the road less time, Hoffman says. “There is more efficiency, added safety and a cost savings because an operator is plowing two lanes at once,” he says. “It doesn’t take the plow operator as long — [he or she] doesn’t have to make a loop and come back — which means less ‘man hours.’”
Fighting Snow “As-it-Happens”
With Twitter, Facebook, streaming media and smart phones, real-time developments are now commonplace.
This concept of using “as-it-happens” information is now being applied to controls in winter maintenance vehicles. For example, Monroe Truck Equipment is working with its controls where a card can be inserted so live radar can be viewed. This would allow plow truck operators to adjust application speed or materials if a storm system is increasing or decreasing, to provide operators with better guidelines on what should be done with a particular storm or weather incident.
Control makers such as Force America and dickey-john have created the ability for operators to receive information and then download it, says Bill Hoffman, chief maintenance and operations engineer for the Nevada Department of Transportation. “The controls can keep tabs on everything for the vehicle and pulls it all together so someone can go in later and see where a truck was, look at the application rates, and even when a plow blade went up and down,” Hoffman says. “That’s been around for a while. But what’s new is taking that information and sending it wirelessly back to a maintenance facility.”
The newest practice states are adopting is populating a management system with it. “A lot of state DOTs have maintenance management or work management system where it logs all of the employee hours, what they were doing, where they were out, how much material they used, etc.,” Hoffman says. “That’s how states track costs through labor, equipment and material.”
Agencies are now working with control makers to have this information sent wireless back in real time to populate their management systems. “Operators may be out fighting snowstorms for 15 hours,” Hoffman says. “Once they get out of their truck, then they have to come in and manually enter all this information into a data system. That’s the last thing they need to be doing after being on the road. We want operators home and rested so they can come back the next day and continue to fight storms.”
If the data is transferred in real time, the operators can finish their shifts and go straight home, Hoffman says. Having this data in real time can also help the public as well. By using controls for real-time road conditions with videos, it can help traffic management system centers with decision support. Additionally, some of the road condition information can be uploaded to public logs on websites so the public can have accurate road conditions. It essentially allows the public to “see” what’s going on with road conditions through the plow operator’s eyes.
iPods are for more than just downloading and listening to your favorite songs. Some U.S. agencies are now using them for Audio Route Technology (ART) — essentially turn-by-turn instructions for snowplow drivers. The instructions can be pre-recorded and traded around. “It’s a lot cheaper than getting a GPS turn-by-turn,” says Bill Hoffman, chief maintenance and operations engineer for the Nevada Department of Transportation. “And a GPS unit might not take you on the exact same plow route each time. It would try to calculate the shortest or fastest distance.”
Hoffman says, although a GPS unit is a great asset in some situations, for a snowplow route, “it doesn’t dial operators in to the level of details a driver usually needs.” With ART, special instructions could be included such as, “This pavement is usually five degrees cooler so application rate should be increased,” or “Railroad crossing ahead; Please lift your plow,” Hoffman points out. “Direction for each and every plow route can be specifically recorded and timed at an approximate plow speed. If someone gets sick, a substitute could just take the iPod and take it on the route.”
Hoffman says he finds this technology so valuable that he is trying to kick-start implementation of it in Nevada. “People know about the benefits,” he says. “I just need to get them to sign on the dotted line. In the winter maintenance community, we are trying to link technology and performance to safety and mobility in the winter. It’s up to winter maintenance transportation leaders to find ways to communicate with public and top transportation officials the need for [continued and increased] funding.”
Blades: It’s not a case of one blade fits all
In fact, the size, material and configuration of snowplow blades have a pretty big impact on how efficiently and effectively roads and highways are cleared, and the Iowa Department of Transportation (Iowa DOT) has been experimenting with just how unique blade configurations can be, says Bret Hodne, public works director for the City of West Des Moines, Iowa, and a current member and past chairman of the APWA Winter Maintenance Committee.
Typically, a plow blade has three elements that make it effective: the cutting angle, down pressure and the thickness. These three components affect how well a blade can cut through snow and ice. “If you try to cut a piece of meat with a dull blade that was 2 inches thick, it would be hard to,” Hodne says. “The thinner and sharper the blade, the more effective it is. It’s the same principle with a knife. You want to be able to slice down through snow and ice, and if you get some down pressure, you can provide better cutting action.”
Front plows typically use the weight of the plow, while a motor grader or underbody scraper will provide down pressure, Hodne explains. “If you can get an optimum blade with down pressure, it promotes excellent cutting action.”
The Iowa DOT and the City of West Des Moines have been experimenting with various types of blades such as the Joma, manufactured by Black Cat. “Both agencies have been using the Joma blades and have had really good success with them,” Hodne says, adding that the price has been falling on the blades so they are becoming more cost-effective for agencies to use.
The Joma blade is mounted by means of a bushed rubber mounting, so there is no metal-to-metal contact between the blade and the plow, which allows the blade to absorb shock transmitted from the road surface. This shock-absorbing feature, in turn, protects the insert from severe impact, so it allows a longer insert life which results in longer wear life. Hodne says that the rubber mount also absorbs most of the vibration — also known as “chatter” — that would normally be transferred to the plow and the truck. Vibration can be a chief cause of many structural failures and also contributes to operator fatigue, so the reduced “chatter” makes it less noisy and more comfortable for plow operators, Hodne says.
The City of West Des Moines has also found the use of a Kyuper blade — ceramic with carbide embedded in it — to be effective in snow and ice clearing. “It’s the same principle as with a single steel blade, but there is greatly increased wear life,” Hodne says.
The biggest experiment going on currently with multiple states has been DOTs working with a handful of snowplow manufacturers (Monroe Truck Equipment, Falls Equipment, Henke, and Viking) in the quest to develop an optimum snowplow configuration. One prototype plow includes a front-cutting blade, followed by one or two other hydraulically-activated blades behind it that provide a squeegee action to clear the residual slush. A rubber-type blade or blades (Iowa DOT has also been experimenting with triple blades) behind the standard front plow blade controlled by the operator can provide very effective plowing action, Hodne says. “When conditions are optimum, the operator can lower down the secondary blades and take off some of the slush or residual material off and achieve a safer pavement condition,” he adds. v
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