Winter Highway Operations (2005)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

25 There are several areas where emerging technologies hold promise for winter highway operations. These include a holis- tic integration of weather forecasts, pavement conditions, and rules of practice in the form of a maintenance decision support system (MDSS). Other examples are the increasing deployment of fixed anti-icing spray systems, fog warning systems, variable speed limits, and winter maintenance route optimization. STORM MANAGEMENT FHWA Maintenance Decision Support System A significant event during the period covered by this synthe- sis is the development of a prototype MDSS commissioned by the FHWA Office of Transportation Operations. The pro- totype was conceived in cooperation with stakeholder state DOTs and operationally tested during the winter of 2002/2003 on selected routes maintained by Iowa. The project goals were to develop a prototype that: • Capitalizes on existing road and weather data sources; • Augments data sources where they are weak or where improved accuracy could significantly improve the decision-making task; • Accomplishes data fusion to make an open, integrated, and understandable presentation of current environmen- tal and road conditions; • Processes data to generate diagnostic and prognostic maps of road conditions along road corridors, with emphasis on the 1- to 48-h horizon (historical informa- tion from the previous 48 h will also be available); • Provides a display capability on the state of the roadway; • Supplies a decision support tool, which provides recom- mendations on road maintenance courses of action; and • Provides all of the above on a single platform, with simple and intuitive operating requirements, and does so in a readily comprehensible display of results and recommended courses of action, together with antici- pated consequences of action or inaction (“Project Description” 2001). Most agencies surveyed at least know that the FHWA MDSS exists. More than 40% report having had key involve- ment or participating at a stakeholder level. One-half of the responding agencies familiar with the MDSS believe it will develop into a useful tool. Key examples identified by the MDSS field testing that are primed for improvement include better near-real-time precipitation information, the value of route thermal map- ping in attempting greater accuracy at determining where and when to apply chemicals, and the importance of blowing snow prediction and treatment. Fixed Anti-Icing Spray Systems Fixed installations to apply anti-icing liquid are relatively new, primarily occurring over the 10 years covered by this synthesis. Several of the responding agencies have installed such systems on roadway sections and structures. Edmonton, Illinois, Maryland, Minnesota, and Washington State all have bridges with fixed spray systems, representing approximately 12 bridges or structures. Nebraska uses the technology on the approach to some bridges as well as a downgrade to a stop- light. Nevada is in the planning stages of incorporating spray systems in new freeway construction. Lengths of roadway covered by the various installations vary from 150 ft to 3,500 ft, over two, three, and four lanes, on two-, five-, and eight-lane roads. A majority of the instal- lations use potassium acetate. Magnesium and calcium chlo- ride are also used, but to a lesser extent. There are many ways in which the agencies have experi- enced integrating these systems into their operations. For Cal- trans, it has reduced the need for storm patrol on an isolated section of road. Less effort by trucks before and early in a storm are benefits cited by Illinois and Maryland, two states that both still spread salt on the structures if storms are in progress or intensifying. Both Maryland and Minnesota have integrated some of their spray systems with an on-site RWIS– ESS. For Maryland, this automation addresses frost control, minor storms, and snow squalls. Minnesota, Nebraska, and Washington State have systems that are manually controlled. The city of Edmonton installed its system only recently, dur- ing the 2003 summer, and did not at the time of this synthe- sis have performance experience to share. Nevada cautioned that conflicts are often encountered between bridge design- ers and operations in installing the systems on structures. CHAPTER SEVEN EMERGING TECHNOLOGIES

Route Optimization The increasing attention to efficient chemical use and resource expenditures drives analysis and planning to a far finer detail than previously. The attachment of actual road surface con- ditions such as solution chemical concentration and pave- ment temperature taken by sensors on the truck to the posi- tion of the truck along the highway network calculated by an on-board AVL receiver becomes significant. This informa- tion can then be processed in terms of the expected route length and conditions, precipitation rates, and the amount of materials still loaded to optimize plowing and spreading activ- ities. This same information has high value as historical rec- ords to optimize, plan, and manage activities on an annual basis. When faced with increasing demands from funding sources to validate expenditures, this type of advanced infor- mation could be increasingly useful. TRAVELER INFORMATION More than 95% of the agencies involved in this study replied that they report winter road conditions regularly to the pub- lic. The advent of 511, a nationally designated three-digit 26 phone number for access to traffic and road condition infor- mation, has provided a standard method for supplying trav- eler information. Most of the responding highway agencies use a combination of the Internet, the media, and telephone services such as a hotline or a 511 system to disseminate the information. Figure 5 shows an example of the types of infor- mation being provided by Connecticut on the Internet. Ore- gon’s TripCheck has won two awards for its concept and design. Users are able to configure their own set of cameras and road reports to meet their travel routes or patterns. A number of agencies use a variety of strategies including the Internet as a means to increase public awareness of winter operation goals and constraints. An excellent example is Cal- trans’ Snow & Ice Control Operations brochure, available as an Adobe Acrobat file on the Caltrans website. Another exam- ple is the Idaho Transportation Department’s website, which provides both current driving conditions by means of the Road Report and a variety of other winter maintenance information to assist the public. Illinois provides RWIS–ESS information on the Internet to allow the public to view at least a portion of the information electronically. Mn/DOT makes remarkable use of their performance measure “Dashboards” in communi- cating with the public. Figure 6 shows an example of this type FIGURE 5 Connecticut road conditions as viewed on Connecticut DOT website. Precipitation codes include: IP (sleet), L (drizzle), NP (no precipitation), R (rain), RIP (rain/sleet), S (snow), SIP (snow/sleet), SW (flurries), Z (freezing rain), and ZIP (freezing rain/sleet).

27 of public education being done by the WSDOT through their website. Many of the agencies reported close coordination between different sections within the agency to manage winter main- tenance, traffic operations, and information handling. The greatest level of cooperation appears to be between mainte- nance and those managing information for public dissemi- nation. Maryland makes use of a communications center or emergency operations center to pass weather-related roadway information to the public, either by means of ITS elements or the media. New Brunswick reported using private call centers to respond to road condition requests. Thirteen of the 22 agen- cies that make use of a reporting system collaborate and share data with adjacent provinces or states. Weather Warning Systems Severe or problematic weather warning is another topic of interest. Nine of 21 agencies reporting indicated that they use severe weather warning systems for fog, visibility, flooded roads, or other conditions. Most of these report using dynamic message signs and/or highway advisory radio systems to warn motorists. Some agencies reported on the use of per- manent features such as signs or delineators in areas with chronically poor visibility. Nevada has installed a high wind warning system on a state route in Washoe Valley. Many respondents reported on the use of visibility sensors in asso- ciation with other RWIS–ESS sensors to detect conditions for which they will then disseminate a warning. Visibility and fog are key issues as cited in a 1999 FHWA Tech Brief that included examples of crashes (Highway Fog Warning System 1999). FIGURE 6 Winter maintenance practices for public information as displayed on the WSDOT website.