National Academies Press: OpenBook

Winter Highway Operations (2005)

Chapter: Chapter Three - State of the Practice

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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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Suggested Citation:"Chapter Three - State of the Practice." National Academies of Sciences, Engineering, and Medicine. 2005. Winter Highway Operations. Washington, DC: The National Academies Press. doi: 10.17226/13828.
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This chapter provides an inventory and discussion of inno- vations, improvements, developments, and advancements made in winter highway maintenance during the past 10 years. It presents a comprehensive and descriptive picture of the practices, enhancements, and technologies in use. In comparing the literature, efforts of leading states and provinces, and agency responses it is clear that there is very little separation between state of the practice and state of the art in winter highway operations. The two levels of technol- ogy and research, integration and adoption, exist between the agencies themselves rather than between the agencies and the researchers or developers of the advancements. Many agen- cies have active participation in applied research programs and frontline practical experimentation. In winter highway operations, every storm, every day, involves adaptation using the same set of methods and materials applied to a new situ- ation that at some levels is very similar to previous ones but never fully the same. Winter maintenance activities take a certain amount of finesse and creativity to accomplish, espe- cially in times of increasing resource constraints. SURVEY RESPONSES The responses of the 22 agencies providing the primary con- tent of this synthesis are presented in Appendix C and are described by topic in the next sections of this report. One question asked respondents was “what tools in their winter operations toolbox are well used?” Several traditional practices, as well as advancements, were described as “well used” tools by the responding agencies. Some of these tradi- tional practices included the use of various equipment, mate- rials, and technologies such as snowplows, sanders, snow- blowers, motorgraders, front-end loaders, salt, snow fences, and two-way radios. Responding agencies cited the following advancements in winter highway operations: • Anti-icing, all-liquid application, and pre-wetting; • RWIS weather forecasts, pavement and weather infor- mation; • Camera images available on the Internet; • Management practices (e.g., salt management plans, storm reports); 8 • Equipment improvements (wider front plows, wing plows, ground speed control units); • Training and winter preparation; • Better communication with the traveling public; and • Information distribution at the winter operations decision- maker level. Another question asked what tools no longer were useful or had been discarded in the past 10 years. A few were men- tioned, such as the use of the 75mm recoilless rifle in high- way avalanche control by the California DOT (Caltrans). Montana has seen the end of cutting snow pack with motor- graders, and California no longer uses liquid deicers directly on snow pack. Indiana, Maryland, and Nevada cited a reduc- tion in the heavy dependence on abrasives. There have been technologies that have been replaced, such as overhead spray systems, mechanically controlled hopper spreader boxes and U-boxes, or gasoline engines (all are diesel now). Quebec included pre-wetting in the not useful category owing to dif- ficulties in integrating it. The survey asked respondents to describe the most sig- nificant changes to winter operations that occurred during the 1994 to 2004 period. New chemicals, all-liquids, and pre- wetting were the most common response with improved equip- ment; RWIS and weather forecast use were also frequently mentioned. Respondents reported upgrades to equipment, improved quality of equipment, and better products for anti-icing as the most common changes affecting winter maintenance opera- tions. Specific key changes to winter operations included: • Addition of pre-wetting, • All-liquid trucks, • Cab controls that are easier to use, and • Ground speed controllers for spreader operation to pro- vide calibrated application. Larger and more powerful equipment has had a signifi- cant impact in reducing the effort required to complete many winter maintenance tasks as compared with 10 years ago. Several key changes cited fall into the information manage- ment category, such as centralized storm management, win- ter operations team (Indiana), RWIS (one of the top three mentioned changes), customer surveys, performance mea- sures, and availability of information on the Internet. Radar CHAPTER THREE STATE OF THE PRACTICE

9access at the decision-maker level was specifically mentioned as an important change. Improved weather forecasts and the use of highway meteorology consultants were singled out as examples of positive change. In recent years, fog and other warning systems have attracted increasing interest at a national level. Under an FHWA-sponsored research project to develop a low-cost, reliable fog sensor, several sensors were fabricated, and bench and field-tested (Highway Fog . . . 1999). Caltrans specifi- cally mentioned the intelligent transportation systems (ITS) technology available through their fog warning system as benefiting winter operations. The Caltrans fog warning sys- tem has evolved to include four districts consisting of three main elements: driver education, enforcement, and a system of sensors and dynamic message signs. Adoption of salt management practices and attention to associated environmental impacts of chemical treatments in general has become increasingly important. This issue has affected operations from 1994 to 2004 as agencies respond to more restrictive environmental constraints such as storm water, storage area, and watershed runoff regulations. For example, the Oregon DOT (ODOT) has implemented best management practices developed specifically for snow and ice removal and sanding in an effort to minimize impacts (Routine Road Maintenance . . . 1999). ODOT also makes a concerted effort to recover abrasives in stream sensitive areas at the end of each winter season. Maintenance funding constraints and changes relating to personnel were referred to as key issues affecting winter oper- ations. Examples of personnel issues included the loss of maintenance workers, increased use of casual or temporary workers, and training. One responding agency, Alberta Transportation, has switched to 100% contract winter main- tenance provided by private industry. Alberta also experi- enced a doubling of network miles for which they are respon- sible, with the transfer of roads from municipalities. It was reported that difficulties accompanied this transfer of respon- sibility owing to only a 20% increase in the snowplow fleet. More than one respondent cited an increase in road miles for which they have maintenance responsibility. Several agencies described the expectations of the public for bare pavement as a factor of increasing importance over recent years. Meanwhile, Saskatchewan indicated an overall decrease in the severity of winter storms over the past 10 years, not- ing lower than average precipitation over the period. Landscaping adjacent to roadways has become increas- ingly prevalent. Its mere presence is another significant issue agencies are dealing with in their winter operations. There is the extra effort of maintaining the landscaping, as well as the effort of minimizing the negative affects that winter mainte- nance actives have on the landscaping. These areas are often no longer available for snow storage, require reduction in plow speeds to avoid damage, and are sensitive to concen- trations of deicing chemicals or abrasives. The importance of maintainability often arises with the inclusion of culture- and technology-driven trends in the form of context-sensitive design. It is increasingly important for maintenance to review plans and specifications at the design stage to avoid long- term difficulties and the associated extra costs. Nevada documented maintenance considerations to be included in the design of the I-580 freeway extension between Reno and Carson City (Kashuba 1999). The design recom- mendations included: • Incorporation of divided alignments, • Non-use of undivided alignments with vertical separation, • Wide shoulders and ditches, • Sound wall use only with sufficient snow storage area (6 m minimum) and no shadowing of the roadway, • Design of standard detail for installation of snow poles in proposed barriers, • Wide medians (15 m minimum) with minimal use of barriers, • Fills to be 0.74 to 1 m above existing grade (i.e., above the surrounding snow surface throughout a “design win- ter”), and • Use of snow fences. SNOW AND ICE CONTROL STRATEGIES The organization of snow and ice control or other winter operation activities by the various agencies follows logical outlines based on the local needs and governmental structure. A common thread expressed by the respondents was “doing more with less” under increasing constraints. Twenty-one (95%) of the responding agencies provide winter maintenance through their own personnel. Alberta uses solely contract personnel. Ten agencies augment their own employees with contract maintenance workers. One of the 10, Minnesota, uses other government employees under contract. Two agencies, Manitoba and Quebec, augment their own employees with both private and other government con- tract personnel. The specific break out is shown in Table 1. Readers interested in good examples of guidelines for con- tract operations are referred to Bourdon’s Best Practices of Outsourcing Winter Maintenance Services (2001). Snow and ice control as conducted by nearly all of the agencies follow organized strategies in the form of written plans, policies, or plow routes. Two state agencies, Maryland and Nevada, stated they do not have a policy manual; how- ever, both do use plow routes. Four of the surveyed agencies, California, Idaho, Nevada, and Vancouver, do have policies, but do not use plow routes.

10 the funds available for other maintenance activities. The base year is reestablished every 2 years. Information collected about costs per lane mile for winter maintenance was sufficient only for summary comparison. The numbers present a picture of dramatic contrast between rural and urban costs. Agencies operating primarily in rural regions are subject to much lower costs per mile than their urban counterparts. The average rural winter maintenance cost per lane mile for 2002/03 was $2,500. Figure 2 graphically represents the cost per mile data provided by the responding agencies. The majority of the agencies use some form of electronic maintenance management system. Only 50% of the agencies tie the costs and budgets associated with maintenance to spe- cific roadway segments, and only Edmonton and Moncton responded that GIS have been incorporated for snow and ice control budgeting and cost tracking. Four agencies, Edmonton, Idaho, Saskatchewan, and Wash- ington State, noted that they had documented benefits result- ing from winter maintenance activities. Idaho analyzed win- ter maintenance activities for 5 years of pre-implementation and 3 years of post-implementation of all-liquid anti-icing on a rural mountainous highway. Their findings are an example of what success can be achieved with a well-planned and A common difficulty experienced by all respondents was obtaining reliable snow and ice control costs. For ODOT, fleet and personnel costs are not easily combined into a sin- gle winter maintenance cost report. Another difficulty is the inclusion of shop or repair costs in the overall winter opera- tions cost. It is generally assumed that more shop and repair costs are required for winter operations than any other main- tenance activities. BUDGETING AND PERFORMANCE MEASURES Several agencies in the survey group provided descriptions of how budgeting for winter operations is accomplished. For many agencies, costs are tracked at the district level. How- ever, Alberta Transportation tracks costs by roadway seg- ment in the management of their contract forces. The metric used by most of the responding agencies for tracking is an activity code, although lane miles, salt usage, and snowplow hours were also identified as cost-tracking methods. Past expenditures are most frequently used for determining budget amounts. Specific historical methods included running 5- and 10-year averages. Maryland sets their snow and ice control budget at a mild-to-average winter level, assuming that over- ages from severe winters will be reimbursed. Nevada operates under a unique situation where funds are set on a zero base budget, with the legislature allocating funds on a biannual basis. In this scenario, severe winters have a direct impact on TABLE 1 PROVIDING WINTER MAINTENANCE (responses by agency) Agency Agency’s Own Employees Improvement District Contract with Private Sector Contract with Government Agencies State/Province Alberta Transportation √ California DOT √ √ Connecticut DOT √ Idaho Transportation Department √ Illinois DOT √ √ Indiana DOT √ √ Manitoba Transportation and Government Services √ √ Maryland State Highway Administration √ Ministère des Transports du Québec √ Minnesota DOT √ Missouri DOT √ Montana DOT √ Nebraska DOT √ Nevada DOT √ New Brunswick DOT √ √ √ Nova Scotia DOT √ Oregon DOT √ √ Saskatchewan Highways and Transportation √ √ √ Washington State DOT √ Municipality City of Edmonton √ √ City of Moncton √ √ City of Vancouver √

11 championed program. Table 2 presents the efficiencies for a specific regional route attained through use of all-liquid anti-icing. The decreases in the use of resources and num- ber of crashes indicated were attributed by Idaho to these changes. Information regarding the use of performance measures is limited. Seven agencies, Alberta, Edmonton, Manitoba, Min- nesota, Nova Scotia, Quebec, and Washington State, addressed this situation. Two respondents (Edmonton and Saskatchewan) have documented winter maintenance benefits. More than half of the responding agencies (12) stated that they do not use performance measures. Two (Caltrans and Illinois) did not respond. This would seem to present an area for advancement and the potential for increased efficiency. Figure 3 shows an example of performance reporting from the Minnesota DOT (Mn/DOT). Through customer surveys the state has determined the expectations of the driving pub- lic (“Dashboards Help . . .” 2004). An example of the desired bare lane is shown on the top left. The graph and dashboard examples are from one of the Mn/DOT maintenance districts. The graph on the top right provides the monthly average for the district over the winter of 2002/2003. The dashboard across the bottom of the figure shows the average number of hours to bare lane broken out by functional class and their respective different time expectations. These dashboards are prominent on their website. For Alberta Transportation, the contractor’s target is stated as achieving good driving conditions within a period of time specific to road classifications. These times are shown in Table 3. Good winter driving conditions are defined to “exist when snow and ice have been removed from the driving lanes and excessive snow has been removed from the shoul- ders and centre line of the highway. Short sections of ice and Ca lif or ni a Co nn ec tic ut Id ah o Ill in oi s In di an a M ar yl an d M in ne so ta M is so ur i M on ta na N eb ra sk a N ev ad a O re go n W as hi ng to n $0 $500 $1,000 $1,500 $2,000 $2,500 $3,000 $3,500 $4,000 $4,500 $ p er la ne m ile Winter 2002/03 Ten Year Max Ten Year Min NA NANA FIGURE 2 Approximate winter operation costs per lane mile as provided by respondents. 1992 to 1997 (without anti-icing) 1997 to 2000 (with anti-icing) Percent of Change Abrasive Quantities 1,929 cubic yards (1,475 cubic meters) 323 cubic yards (247 cubic meters) 83 Labor Hours (annual) 650 248 62 No. of Crashes (annual) 16.2 2.7 83 Source: Breen 2001. TABLE 2 IDAHO TRANSPORTATION DEPARTMENT’S EXAMPLE OF IMPROVEMENTS AS A RESULT OF ALL-LIQUID USE

packed snow are acceptable and can be expected between the wheel paths, as well as on the centre line.” WSDOT used a single performance measure to report a level of service (LOS) rating for snow and ice control activ- ities. The measure takes into consideration the traction con- ditions (i.e., presence of traction owing to anti-icing chem- ical, sand application, or plowing) on the travel lane road surface and is observed and documented during periodic field condition surveys. The traction conditions are determined by returning to the route after a designated period of time has past since the last plowing or sanding and examining all travel lanes between given mileposts. Bare pavement is the condi- tion if at least 95% of the roadway surface is free of ice and/or snow. The roadway is considered sanded if at least 60% of the travel lane has sand on the surface. To allow for simple field analysis, 60% coverage is considered equal to a 12 travel lane with bare tire tracks and sand on the remainder of the lane. This is somewhat time and travel intensive and is in addition to normal storm fighting efforts. PLOW ROUTES AND MATERIAL APPLICATION DECISIONS Slightly more than 80% of the respondents stated that they used plow routes. Four of the surveyed agencies, California, Idaho, Nevada, and Vancouver do not use plow routes. The agencies that use plow routes use various methods to deter- mine them including: • Staffing and performance or LOS targets; • Functional classification and average daily traffic; • Emergency service locations and/or transit routes; • Maintenance shed or garage area; FIGURE 3 An example of graphics that Mn/DOT provides to customers. A bare pavement definition is shown (upper left), along with graphs (upper right) and dashboards (bottom) (“Dashboards Help Drive Mn/DOT Performance,” http://www.dot.state.mn.us/dashboards). Segment Classification Segment Characteristic Maximum Time to Good Driving Conditions Following End of Storm Class A >7,000 AADT 6 hours Class B 5,000 to 7,000 AADT 6 hours Class C 2,000 to 5,000 AADT 8 hours Note: AADT = average annual daily traffic. TABLE 3 ALBERTA TRANSPORTATION CONTRACT ADMINISTRATION REQUIREMENTS FOR SNOW REMOVAL AND ICE CONTROL

13 • Lane miles (may cross shed or district boundaries); and • Combination of climate, geography, and contractor proximity. The routes are generally changeable once the storm begins, except in cases where they have been determined to coincide with emergency or transit routes or by contractor assignment. Those that are changeable usually adapt to practical constraints such as storm conditions, equipment availability, personnel shortages, or a less than worse case scenario for which the route is designed. A specific example of what happens as a result of route changes is that the segment of lowest LOS drops in priority; for example, is postponed until later. Changes in routes are made by a combination of input from frontline and supervisory levels as based on local institutional guidelines. The frontline equipment operator has decision-making authority in the application rate of chemical, abrasive, or com- binations in slightly more than 50% of the surveyed agencies. This is a subset of localized authority at the maintenance-shed level used by nearly 85% of the responding agencies. Three of the respondents, Montana, Nevada, and Ore- gon, set the application rates at a headquarters level and in one case allow the front line operator to adjust the rates for reapplications. STORM CLEAN-UP Agencies identified a number of tasks associated with storm clean-up plans. In general, plowing plans based on safety and the importance of routes sets priority. This priority is also fre- quently dependent on time of day relative to traffic peaks and daylight. The tasks include the following: • Clearing driving lanes, bridges, and ramps by plowing or blowing; • Clearing shoulders and approaches; • Resolving site distance problems by pushing snow back or removing snow piles; and • Clearing gore areas, signs, and maintaining drainage. In addition, some agencies must focus on using ice-cutting motor patrols to remove ruts. Some agencies report that they sweep, recover, or recycle abrasive materials, particularly in sensitive areas. These agencies include the city of Edmonton, Nevada DOT, ODOT, and WSDOT. Nevada sweeps in air quality nonattainment areas. DECISION SUPPORT The increasing use and reliance on RWIS data and road weather forecasts was cited as one of the primary changes to winter highway operations. Responding agencies did not sin- gle out pavement temperature forecasts in their replies. All state and provincial agencies provide access to weather fore- casts for winter operations decision makers. Of those, approx- imately 16% use a private contracted forecast service exclu- sively, whereas 37% use a government agency forecast service such as Environment Canada or the National Weather Ser- vice, and the remaining 47% use a combination of contracted and government-provided forecasting services. The agencies typically access the forecasts from the Internet or facsimile and frequently use more than one method to obtain this infor- mation. Other methods used include telephone, e-mail, radio, and satellite transmission. Most agencies receive updated forecasts between two and six times daily in the regular course of operations and increase this frequency as needed during winter storms. INFORMATION MANAGEMENT This area represents the greatest advancement during recent years. There is a far greater number and more extensive uti- lization of information sources and mechanisms in use at the time of the synthesis than 10 years ago. These sources include print, electronic, and interactive. One particular published source of information providing extremely valuable and use- ful information, printed within the past 10 years, is the 1999 AASHTO Guide for Snow and Ice Control. The FHWA Manual of Practice for an Effective Anti-Icing Program: A Guide for Highway Winter Maintenance Per- sonnel, provided a valuable and needed basis for incorpora- tion of the methods and technology (Ketcham et al. 1996). This was followed by Test and Evaluation Project No. 28, which culminated in the Anti-Icing Technology, Field Report (Ketcham et al. 1998). This report included results and inter- pretations, cost analysis, recommendations for practice, and conclusions regarding the state of the art of anti-icing. Another recently published source of valuable informa- tion is the FHWA Road Weather Management Program’s Best Practices for Road Weather Management Version 2.0 (Goodwin 2003). This resource contains case studies from every region of the country, a listing of road weather publi- cations, an overview of environmental sensor technologies, and on-line resources. The use of the Internet has become so commonplace and habitual that it is difficult for most maintenance personnel (frontline or management) to describe let alone remember their level of Internet use 10 years ago. It is currently used for access and delivery for nearly all RWIS information and data except in cases of satellite information delivery (e.g., Weather Ser- vices Inc. and Meteorologix. The Internet has ended the geo- graphic separation and accessibility of individuals wishing to discuss common topics. An example of its success is the snow–ice list server maintained by the University of Iowa Insti- tute of Hydraulic Research Hydroscience and Engineering Department and supported by AASHTO’s SICOP. This server connects management- and administrative-level planners and

decision makers for winter highway operations throughout the world by means of e-mail. The significance of this resource is imaginable in terms of realizing its potential to completely replace this document in a timely and question-specific man- ner. All a maintenance manager has to do is pose a question to the group such as, “what is the most cost-effective winter oper- ation technology you use and why?,” sit back, and wait for the response from every road weather climate and size of operation extant. It is important to note that the information is not peer reviewed other than through each reader’s comments, correc- tions, or replies to statements made in response to the ques- tions posed; that is, responses must always be put to a rele- vance and correctness test before basing actions on them. Even with this caveat, the inquiry and exchange of experience and information among this group has enhanced and advanced winter operations at various local levels in an immeasurably successful manner. Two examples of additional use of the Internet in making valuable winter operations information widely available are the FHWA winter maintenance virtual clearinghouse and SICOP websites. The Internet has also connected the agencies with their customers in a highly cost- efficient and valuable way as will be described later under traveler information (see chapter seven). OPERATIONS The discussion of operations is divided into five subtopics: Pri- mary Field Operating Conditions, Equipment, Materials, Tra- ditional Activities, and RWIS. Traditional activities include classic methods such as snow removal with truck-mounted plows, maintaining the driving surface during storms, storm clean-up, and controlling blowing snow with snow fences. Primary Field Operation Conditions Winter maintenance personnel encounter a variety of adverse pavement conditions that need to be addressed in accomplish- 14 ing their activities. One survey question asked the agencies to rank the winter pavement conditions that most effect their operations, segregated by urban, suburban, and rural geogra- phy. Frontline maintenance personnel are frequently already attuned to issues that are seemingly uncovered in scientific analysis of data collected from a more diverse and geographi- cally dispersed study. It is possible that the description of pri- mary field operation conditions falls within this category. A somewhat surprising picture of the distribution emerges from the survey results. At a frontline level, blowing and drifting snow may seem like a big problem; however, because it is quite location specific, it might not be considered a major prob- lem affecting the winter maintenance community as a whole. Rural drifting snow was ranked the number one problem by 73% of the responding agencies. When the primary and secondary problem responses are combined, suburban and rural blowing snow is the most prevalent problem faced by 100% of the agencies. Clearly, blowing snow presents an arena for improvement in deployment focus and assistance. Tabler’s Controlling Blowing and Drifting Snow with Snow Fences and Road Design (2003) is a valuable and timely update of his earlier 1994 Design Guidelines for the Control of Blowing and Drifting Snow. The development of suburban snowpack is a primary con- cern of 71% of the responding agencies. Combining the pri- mary and secondary problems indicates that rural, suburban, and urban snowpack; suburban black ice; and urban and sub- urban frost are the most significant problems. The results of this question are presented in graphic format in Figure 4. When municipalities’ answers are separated, they rank development of snowpack and black ice as their primary concerns. Equipment Equipment includes the communication methods used within the winter maintenance vehicles, the type of trucks and Urban Suburban Rural 0% 25% 50% 75% 100% Sn ow pa ck Fr os t Bl ac k I ce Fr ee zin g R ain Ice pa ck Bl ow ing S no w Dr ifti ng S no w Bl ow ing S no w Sn ow pa ck Bl ac k I ce Fr os t Fr ee zin g R ain Dr ifti ng S no w Ice pa ck Bl ow ing S no w Sn ow pa ck Dr ifti ng S no w Ice pa ck Fr os t Bl ac k I ce Fr ee zin g R ain Primary Problem Secondary Problem Rare No Response FIGURE 4 Problematic winter pavement surface conditions categorized by the regional characteristics.

15 their components, and the material holding and application equipment. Communications Communications with maintenance trucks is predominately through the use of two-way UHF/VHF and trunk system radios. Seven of the respondents (41%) have deployed 800 MHz systems. Alberta, Manitoba, Nebraska, Saskatchewan, and Washington State cited cellular phones as a method of communication, with Vancouver relying solely on cellular technology. Surprisingly, 45% of the agencies reported significant problems with their communication systems. The most com- mon problem is inadequate coverage owing to dead spots caused by terrain or a lack of repeaters. Limited channel capac- ity as well as the limited functionality of 800 MHz systems in mountainous terrain were also cited as technological prob- lems. The drawback associated with cellular communication during emergencies as a result of inadequate capacity was also mentioned. Logistical problems associated with commu- nication to field personnel were also described. These prob- lems include radios being fixed within the vehicle and there- fore not useful when crews are outside the truck, and the lack of interoperability with other agency radio systems. An important trend is seen in the rise of problems associ- ated with increased on-board computerized systems. Inter- ference by radios with other electronic systems was reported by three agencies. Trucks The common response from agencies in all road weather cli- mate categories indicated the use of a fleet of both two- and three-axle trucks with a gross vehicle weight range of 25,000 to 50,000 lb for snow and ice control. Horsepower ratings for these vehicles range from 250 to 300 for trucks without a plow wing and from 325 to 400 for those equipped with a wing. A handful of state DOTs have initiated concept vehicle projects. Under these efforts new technologies and ideas for integrating advanced navigation, surface pavement condi- tion, chemical application, driver environments, and others are being tested in actual over-the-road snowplows. It is anticipated that this area will offer the greatest possibility of advancement in equipment and its operation over the next few years. Attempts to collect information about changes in the equip- ment that maintenance departments own and use was limited in its success. Many agencies lack resources to effectively research records regarding past operations and were, there- fore, unable to provide data. For the agencies that were able to provide data, there were only minor changes in the num- ber of trucks as categorized by how they are equipped; with only a plow, only a spreader, both a plow and spreader, or all- liquid trucks. Responding agencies with primarily rural main- tenance responsibilities on average own and operate approx- imately 1,000 trucks total. However, there have been some noteworthy changes in equipment usage. For example, in Maryland, the fleet of motorgraders used has more than tripled; whereas, in con- trast, in other states the use of motorgraders to remove road- way ice pack has decreased. There also appears to be a slight increase in use of snowblowers, particularly in rural plains applications. There has been a dramatic increase in the use of pavement temperature sensors on winter maintenance vehicles. In 1994, very few (less than 1%) winter maintenance vehicles had this equipment; whereas, an average of 30% of the vehicles had pavement temperature sensors at the time of this synthesis. This trend tends to indicate an increasing effort to provide more pavement-specific information to the equipment oper- ator while on task, where it can make the most effective dif- ference in efficiencies. It is important to note that the accu- racy and relevance of the temperature data provided by these sensors is highly variable and dependent on mounting, use, and interpretation. Tabler (2003) provides insight to this prob- lem in the results of a recent study. Plow Blade Types Plow blade types include one-way-only, V, and reversible, and can be used on either plow trucks or motorgraders. Some motorgraders are equipped with more than one blade for snow removal. Reversible-type blades are used on approxi- mately two-thirds of the plow trucks; whereas approximately one-quarter use one-way-only blades, with the remainder being equipped with V-type blades. Motorgraders in use for winter maintenance are generally equipped with a plow blade mounted at the front of the vehicle in addition to the grader blade. More than 60% use reversible blades for plowing snow and approximately 30% use a V-type blade. The use of wing plows has also increased in rural areas and is somewhat more widespread in Canada than in the United States. The New Brunswick DOT reported that all of its trucks have been equipped with wing plows for at least 10 years. Maryland use wings with benching capability. Alberta, Missouri, and Saskatchewan noted using advance- ments made in their plow designs. Maryland uses rubber blades on some plows, as does Oregon. Oregon also uses ultra-high molecular weight polymer moldboard plows. One improvement based on research is the flush-mounted, carbide insert at the front edge of the blade and a non-zero clearance angle (Nixon 1993).

Spreaders Application of solids and liquids requires the interaction of three components: (1) box, bed, hopper, and/or liquid tanks; (2) spinner or nozzles; and (3) application rate controls. The term spreader is used interchangeably in respondent’s answers to mean the box or the distribution spinner, or the combination of both. The largest spreader box capacity used by the responding agencies is 15 cubic yards. The overall aver- age size of spreaders described was 8 cubic yards. Spreader box types (hopper, v-box, slide-in, and tailgate) and spinner locations (rear, behind cab, and underbody) are chosen to fit operational experiences and constraints by all the responding agencies and represent the full range of styles. More than 95% of the agencies that calibrate do so on an annual basis. Several report that calibration is also performed when repairs or changes are made to the equipment or material. Indiana indicated that it attempts to accomplish annual calibration, but that it varies from year to year. Edmonton calibrates both monthly and annually. Montana and Oregon responded that they did not calibrate their spreader distribution rates. The balance of the respondents have adapted or adopted com- monly known methods to calibrate their spreaders. Some of these include trust in the settings of the electronically auto- mated settings, verification of settings through catch and mea- sure, and various calculations based on equipment speed, chain speed, spinner revolutions, auger revolutions per minute, correlation to ground or vehicle speed, and physical distance versus change in load. The calculations used in calibration are represented by Nevada, which has been highly successful using the Salt Insti- tute’s spreader manual calibration sheet provided in The Snow- fighter’s Handbook (1999) to calibrate older spreaders that make up 20% of their fleet. Many agencies reported methods to ensure that spreaders maintain calibration and perform at the desired level. Alberta Transportation monitors contractor performance with a spot calibration check of 5% of the units. Others vary among operator-related methods such as a card kept inside the truck and turned in, driver judgment based on route length or one of the following metrics: • Electronic controls, • Weekly maintenance management system validation, • User information versus data, • Random checks, and • Third party to the operator. Nebraska indicated that calibration was hard to truly know, because operators changed the settings after calibration. In 1994, few agencies reported using truck pre-wetter sys- tems; however, all reported that they now use them to some 16 degree. On average, these systems are used on 40% of the trucks of the responding agencies. Computerized controls associated with spreading rates for both liquids and solids represent a significant change in equip- ment available over the 10 years surveyed. Not surprisingly, the use of computerized spreader controls has increased, with 95% of responding agencies reporting increased use. Wide- spread use started much earlier in Canada then in the United States. Computerized spreader controls are typically used on two-thirds of the winter maintenance vehicles by the organi- zations surveyed. Seventeen of the responding agencies described the use of computerized spreader controls. Montana, Nebraska, and Nevada indicated that in-cab data collection technologies allow for better control of materials application. The reduction of application rates, better assurance of appropriate amounts, and daily availability of data are given as benefits of these systems. Manitoba was still monitoring the introduction of spreader controls and data collection. Indiana commented that acceptance has been slow, but is growing. Key problems expe- rienced by the responding agencies included inadequate min- imum capacities of the hydraulic system, too may wires and connectors, and corrosion problems with wiring connections. Materials The use of chemicals other than sodium chloride (NaCl), all- liquids, and pre-wetting were the most common change in winter operations over the 10 years surveyed. Specifically, the addition of pre-wetting and all-liquid trucks along with the inclusion of easier cab controls and ground speed con- trollers for spreader operation were key changes to winter operations of the survey group. Abrasives Every agency that responded reported the use of abrasives; however, it was clearly indicated that this use is being dis- couraged because it is not a deicing agent and requires clean-up owing to PM-10 (particulate matter smaller than 10 micrometers) air quality standards. Other problems expe- rienced by states including California, Nevada, Oregon, and Washington involve reducing the amount and potential of the abrasives entering rivers, negatively affecting the riverbeds. Some agencies including California, Edmonton, Nevada, Oregon, and Washington State, reported that they sweep, recover, or recycle abrasive materials, particularly in sensi- tive areas. Chemicals The majority of the responding agencies use NaCl in either solid or liquid brine form as an anti-icing, deicing, or pre- wetting chemical. The cities of Moncton and Vancouver, as

17 well as Connecticut and Nova Scotia, use salt as their sole chemical. The northwestern states of Oregon and Montana do not use road salt at all. For the balance of agencies calcium chloride (CaCl) is the predominant chemical. Six of the 14 agencies specifically cited use of a corrosion-inhibiting additive. A higher propor- tion of users of magnesium chloride (10 of the 11) specifi- cally mentioned products with corrosion inhibitors. Alberta, Illinois, and the city of Moncton responded that they apply corrosion inhibitors to their fleet. Only WSDOT replied that they use the complex chloride containing sodium, potassium, and magnesium chlorides. The chemical use by reporting agency can be seen in Table 4. One of the changes that occurred during this 10-year period (1994 to 2004) was the formation of groups such as the Pacific Northwest Snowfighters Association (PNSA). This organization of state, province, and municipality highway agencies developed specifications leading to a qualified prod- uct list of snow and ice control chemicals. The specifications are found on the PNSA website. TABLE 4 ANTI-ICING, DEICING, AND PRE-WETTING CHEMICALS USED BY SURVEYED HIGHWAY AGENCIES Alberta Transportation California DOT Connecticut DOT City of Edmonton Illinois DOT Indiana DOT Idaho TD ManitobaTransportation & Govt. Services Maryland State Highway Admin. Minnesota DOT Missouri DOT City of Moncton Montana DOT Ministere des Transports du Quebec New Brunswick DOT Nebraska DOT Nova Scotia DOT Nevada DOT Oregon DOT Saskatchewan Highways and Transportation City of Vancouver Washington State DOT NaCl NaCl Brine CaCl CaCl Inhibited MgCl NaCl CaCl CMA Kac NaCl Inhibited Complex Cl MgCl Inhibited Agency MgCl Notes: NaCl = sodium chloride; CaCl = calcium chloride; CMA = calcium magnesium acetate; Kac = potassium acetate; MgCl = magnesium chloride.

All-Liquid The average all-liquid truck capacity is 1,700 gal. Missouri uses both the largest maximum size of 6,000 gal and largest average size of 5,000 gal. Idaho and Nevada also use larger than average size all-liquid trucks, reflecting their successes in incorporating all-liquid methods in their snow and ice control activities. The efficiency of large all-liquid trucks is championed by Missouri, which reported that one 5,000-gal tanker replaces two or three dump trucks with small tanks. Minnesota provided application rates, the highest at 1,200 gal per lane mile, with an average rate of 300 gal per lane mile. The manner in which all-liquids are applied has changed over the surveyed 10 years for 70% of the agencies. Nevada did not use all-liquid methodology before 1994 and Alberta deployed this technology in 2001. Improved technology has been a major change in this treatment strategy, greatly increas- ing the accuracy of application. All-liquid methods have been driven by needs to reduce salt use, environmental con- cerns, and economic constraints. They have also been driven by the desire for increased LOS. The inclusion and success of on-board pre-wetting of abrasives or chemicals has also prompted increased reliance on liquids. Enhancing this and representing a significant change is the need for increased experience and training. The Montana DOT serves as a unique example of an agency that has made changes in their application of all liquids. The state has transitioned to a just-in-time response to storm con- ditions. They wait for a 100% assurance that a storm event will actually occur before all-liquid application, rather than basing their decision on a forecast. This approach is a result of efforts to reduce waste, avoid extra costs, eliminate unnecessary vehi- cle exposure to corrosion, and improve public relations. Preliminary research on slippery conditions caused by all-liquid applications has occurred during recent years with nondefinitive findings; however, it was suggested to monitor incoming humidity levels, especially during the fall season (Leggett 1999). All-liquid applications can yield good results; however, it is not as forgiving as traditional application of solids. The recommendation of the early research suggests that combining such humidity monitoring with prudent appli- cation rate and frequency should reduce the likelihood of this problem occurring. Oregon began a research project in 2003, focusing on the reduced skid resistance caused by anti-icing applications. A survey question attempted to ascertain the general level of awareness of this issue and need for further research. More than 31% of the agencies responded that they did not feel that adequate information was available to avoid unintended consequences of all-liquid applications. TRADITIONAL TECHNOLOGIES There are several winter maintenance operations that can be considered traditional activities including the use of various 18 equipment, materials, and technologies such as snowplows, sanders, snowblowers, motorgraders, front-end loaders, salt, grit, and two-way radios. What were emerging technologies 10 to 20 years ago (e.g., snow fences and RWIS) are now reported as traditional uses by a majority of agencies. Snow Fences Seventeen of 20 agencies reported using snow fences. Approx- imately equal numbers of agencies reported using temporary, fixed, and living snow fences (e.g., tree or shrub hedges). Some highway organizations use snow fences extensively, with liv- ing snow fences becoming increasingly popular. Examples include Oregon, which reports 30 mi (48.3 km) of roadway centerline protected by fixed snow fencing; New Brunswick, which reports 6.2 mi (10 km) of roadway centerline protected by living snow fencing; and Alberta Transportation, which reports a total of 237 mi (381 km) of cumulative snow fencing with all types combined. Only 41% of the responding agencies that use snow fences reported having an annual maintenance and repair plan and budget for snow fencing. Other Blowing Snow Control Methods The WSDOT has installed and tested vortex generators, orig- inally designed to keep Antarctic runways free of drifting snow, on segments of Washington highways in efforts to alleviate drifting snow in the winter and drifting sand year round. Caltrans has installed jet roofs on ridgelines above selected highways to alter the wind flow and reduce the development of avalanche hazard. ROAD WEATHER INFORMATION SYSTEMS Use of RWIS has become a mainstream technological methodology in the winter operations toolbox. In 1994, the use of RWIS was fairly widespread geographically; how- ever, it has become an even more essential component to winter operations and is increasingly used by traffic opera- tions. RWIS is multi-faceted, owing to its electronic nature, communication methods, integration requirements, and road- side geographical deployment. This is evident in the various divisions within DOTs responsible for operation and mainte- nance of their systems. Often the responsibility is divided between operation or use groups and support or system main- tenance. Support is most often accomplished at the headquar- ters or regional communications, electronics, or ITS levels. Central support is also a common source for server responsi- bility. Operation of the system is predominately at the district maintenance level. Vendor support and federal government (Canada) support are also cited in two instances (Indiana and Moncton) as the parties responsible for maintenance and oper- ation of the system.

19 Deployment Most agencies own and operate the majority of their auto- mated weather stations. However, Washington State relies on a far greater overall number of stations at 430 than any other agency for which data were collected. Of these, 75% are owned by entities other than the WSDOT. Idaho simi- larly makes use of a significant number of weather stations that it does not own. These two agencies have proven the usefulness and benefits of exchanging weather data with other parties. Eighty-two percent of those agencies that use automated weather stations incorporate pavement sensors with at least some of the stations. Some agencies use more than one pavement sensor at a single automated weather station. Nine of the responding agencies currently use National Transpor- tation Communications for ITS Protocol (NTCIP) for ESS. There are many remote deployment issues that the agencies face including power, communication costs, and impacts to maintenance costs owing to travel distances for centrally based electronics personnel. Although increased use and expansion of RWIS are described as significant changes in the way winter operations are conducted, 50% of the responding agencies have no deployment strategy or criteria for locating RWIS sites. Idaho, Indiana, Minnesota, Oregon, and Nova Scotia responded positively in this regard. In addition, Alberta, New Bruns- wick, and Washington State indicated that this was an effort currently under development or in the preliminary stages. Nebraska presently deploys only to trouble spots, rather than to provide a more comprehensive picture of weather data. In 2003, two federally funded projects were begun with regard to siting standards and pavement sensor calibration. Information Access Seventeen of 22 reporting agencies provided first-hand access to roadside weather information and pavement surface con- ditions for the individual winter operations decision mak- ers. The individual winter operations decision maker does not have access to roadside weather and pavement infor- mation from RWIS–ESS in two of the municipalities, three provinces, and one state. This appears to be the exception, because of the 16, more than three-quarters use some com- bination of agency systems and vendor support to provide this access by means of the Internet or on an internal agency-owned network. In Oregon, the ITS unit is working to standardize access to road weather information to appro- priate personnel. There are several particular cases where the information is available only on the agency intranet or at a single workstation. Indiana was in the process of deploy- ing an RWIS at the time of the survey. Edmonton and New Brunswick reported the use of vehicle-mounted infrared pavement temperature sensors as their primary access to road weather information. Road Weather Forecasts All of the responding agencies provide access to weather forecasts for the individual winter operations decision maker. The most common access is simply the Internet. The cases where agencies responded otherwise were Canadian munic- ipalities, which follow fairly rigid organization of winter oper- ation efforts; that is, policy, plow routes, etc. However, infor- mation access and adaptability at the operator level is good. The respondents use a mix of general forecasts (e.g., National Weather Service, Weather Channel, and Meteorologix), fed- erally provided tailored forecasts (e.g., Environment Canada), and consultant highway meteorology firms (e.g., Meridian, Northwest Weathernet, and Surface Systems Inc.) No ques- tion specifically asked about the use of pavement tempera- ture forecasts. Advancements The agencies were asked how their use of weather informa- tion and deployment of roadside weather stations has changed over the period from 1994 to 2004. Fifteen agencies indicated that deployments have increased. For example, Nevada went from no stations in 1994 to 47 in 2003 and Washington State from a dozen to more than 65. Montana deployed all of its sites during the first half of the 10-year period. Increased resolution and reliance on highway meteorology consultant weather forecasts provided by a surface transporta- tion weather information service was cited by three agencies. During the late summer of 2003, Transport Canada announced a federal initiative toward development of a national RWIS. Federal subsidy through ITS funding within their Strategic Highway Infrastructure Program is designed to support deployment of RWIS–ESS and the nationwide integration of all sites, including the existing 150, to provide consistent information to all jurisdictions. Only two of the agencies (Quebec and Saskatchewan) did not have some remote weather sensors in place in 1994 and just began deployment of RWIS systems during the follow- ing 10 years. For three others, no significant change other than wider use has occurred over that period. Some of the changes cited by the agencies included: • More informed decision making, • Use of the data with training, • Availability of data at more levels, • Greater numbers of roadside installations, and • Movement toward statewide networks. One of the most significant changes has taken place in Montana where, currently, winter maintenance activities such

as anti-icing do not occur until actual conditions change, rather than being based on a weather forecast. Increased use and reliance on pavement temperatures obtained from truck- mounted sensors not available 10 years ago is a change described by several agencies. A 2-year study of the Wyoming RWIS, published in 1998, indicated that the system would facilitate and improve main- tenance operations and enhance the safety and convenience of highway travel if certain critical improvements were made (Tabler 1998). Without these improvements, benefits were expected to be marginal and continued operation might not be cost-effective. Key areas identified for improvement that have cross-agency relevance included the following: 20 • Integrating separate systems; • Improving data displays and simplifying use; • Including supplementary weather information such as NEXRAD (Next Generation Radar, which can mea- sure both precipitation and wind), satellite images, and weather maps; • Making RWIS data and weather information directly accessible in every maintenance station; • Improving site selection procedures; • Providing additional training of maintenance staff; • Providing high-quality weather forecasting services; • Determining adequate sensor selection for recognition of blowing snow conditions; and • Dedicating personnel to manage and maintain the system.

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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 344: Winter Highway Operations examines changes that occurred between 1994 and 2004 to practices and strategies used to control the impacts of winter weather on the safe and efficient movement of traffic.

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