Where the Weather Meets the Road A Research Agenda for Improving Road Weather Services (2004) / Chapter Skim
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4 Opportunities to Enhance the Road Weather System
4 Opportunities to Enhance the Road Weather System
Pages 76-126
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From page 76... ...
Thus, the committee recommends that a focused and coordinated national road weather research program be established to provide leadership in defining priorities, supporting the necessary research, and implementing operational infrastructure. With an improved overarching direction for the road weather community, there are substantial opportunities to produce improved products of interest to the user community through increased coordination of efforts (e.g., Nixon, 2001)
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From page 77... ...
an infostructure that takes advantage of new technologies to effectively monitor and predict road conditions and then effectively convey road weather information to end users. Opportunities for improving understanding, capabilities, and products in these areas of a new road weather research program are discussed in the following sections.
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From page 78... ...
along roadways to obtain tar geted road weather observations. Data from ESS are essential to detecting and forecasting the effects of weather events on the roadway; however, they fall significantly short of the total amount of weather information needed to do this job well.
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From page 79... ...
Data on the road surface and subsurface composition are valuable inputs to pavement temperature models, in which the heat balance is affected by what is under the surface as well as what is above it. Research must be done to determine how changes in this profile affect the road surface and what would be the most efficient way to use this information to obtain more accurate pavement forecasts.
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From page 80... ...
80 WHERE THE WEATHER MEETS THE ROAD TABLE 4-1 Existing and Potential Observations That Should Be Applied to Road Weather Research and Operations Road Weather Observation Description Operated By Application Limitations Automated About 1,000 surface · Federal Aviation Provides weather · Observations are Surface sites providing Administration observations used representative of small Observing observations of sky · Department of as input to area directly adjacent System and visibility, Defense numerical weather to site pressure, temperature, · National Oceanic prediction models · Mostly sited to meet dewpoint temperature, and Atmospheric to ascertain aviation requirements wind, and precipitation Administration/ real-time weather · Lack of good winter amount National Weather conditions on a precipitation Service mesoscale basis observations and aid in weather forecasting Automated Over 600 surface sites · Federal Aviation Provides weather · Observations are Weather providing observations Administration observations used representative of small Observing of wind data, · State, local, and as input to area directly adjacent System temperature, dewpoint private numerical weather to site temperature, visibility, organizations prediction models · Mostly sited to meet present weather, to ascertain aviation requirements precipitation, cloud real-time weather · Lack of good winter height, thunderstorms, conditions on a precipitation and lightning mesoscale basis observations and aid in weather forecasting Various Similar observations as · Oklahoma Provides weather · Observations are surface ASOS operated on a Mesonet observations used representative of small mesonets regional basis with · Atmospheric as input to area directly adjacent higher density of sites Radiation numerical weather to site Measurement prediction models · Sited to meet needs of Cloud and to ascertain specific mesonets Radiation Testbed real-time weather · Data are not always · Many others conditions on a easily accessible across mesoscale basis mesonets and aid in weather · Lack of quality control forecasting and standards Environmental A complement of Individual states or Provides most · Observations are Sensor atmospheric sensors municipalities direct observations representative of small Stations adjacent to the roadway of roadway area directly adjacent (air temperature and environment to site dew point, wind speed · Individual networks are and direction, and not linked optionally, pressure, · Insufficient standards precipitation occurrence, for instruments and other precipitation siting
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From page 81... ...
, and sub-surface temperature probes Aircraft Observations of Aeronautical Input to numerical Not directly relevant to Communication temperature, humidity, Radio, Inc. weather prediction the roadway Addressing and wind collected on models and as aid environment and Reporting commercial aircraft up in weather System to 15 km altitude forecasting In situ Observations of air and Some prototypes · Information · Challenges in observations surface temperature, being developed provided directly communicating from vehicles humidity, surface and tested, but not to drivers observations on the roadway friction, and visibility in yet operational · Input to road · Possibility for more the roadway weather forecasts observations than can environment · Input to be usefully applied numerical weather prediction models Weather Nearly continuous · National Weather Input into · For NEXRAD, scans radars, monitoring of Service numerical weather below 0.5° above including precipitation, including · Federal Aviation prediction models horizon not permitted NEXRAD severe weather, and an Administration (e.g., the Weather so areas distant from ability to determine · Private sector, Research and radar not well winds and detect including Forecasting model)
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From page 82... ...
82 WHERE THE WEATHER MEETS THE ROAD TABLE 4-1 Continued Road Weather Observation Description Operated By Application Limitations Wind and Remotely sensed · National Oceanic · Input into · Representative of a temperature observations of and Atmospheric numerical small area profilers temperature, moisture, Administration weather · Network not very and wind up to 16 km · Other state and prediction dense above the surface federal agencies models · Academia · When combined · Private sector with SODARS, the 900-MHz band profilers can be used for microscale modeling of the roadway · Improve weather forecasts Geostationary Observations at · National Oceanic Improve weather Cannot resolve features Operational multiple wavelengths and Atmospheric forecasts on the roadway Environmental (e.g., visible, infrared, Administration Satellite, Polar microwave) used to · National Orbiting derive, for example, Aeronautics and Environmental integrated water vapor Space Satellite, and and cloud-track winds, Administration other satellites tropical cyclogenesis · Military Traffic Traffic detectors and Individual states · Managing the · No standard format or observations cameras or municipalities traffic system reporting procedure during inclement · Expensive to store weather · Input to energy balance models · Study of weather impacts on traffic Recent Data record indicating Individual states Input for No standard format or treatment the chemical or municipalities forecasting road reporting procedure history application, plowing, surface conditions or sanding of a given and providing stretch of roadway decision support for further treatments Roadway Surface and subsurface Individual states Input for energy Network not very surface and sensors used to or municipalities balance models dense subsurface measure temperature that forecast road surface temperature
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From page 83... ...
Recommendation: Take advantage of existing observation networks and databases. The committee recommends that the road weather research program take full advantage of established environmental monitoring networks, including those from in situ and remote-sensing platforms and existing databases on soil type and land use characteristics.
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From page 84... ...
Having access to these data in standard formats would allow private sector companies to de velop forecasting tools that could be easily and reliably applied in different states. Expand the Network Exploiting weather information to increase the efficiency of the road way system requires weather, road condition, traffic, and other observations that are representative of the roadway.
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From page 85... ...
To attain an improved road weather observation network the road weather research program should support efforts to establish standards for observing procedures and station siting to ensure that (1) the data are representative of the roadway environment and (2)
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From page 86... ...
The majority of research and development of environmental sensors takes place in the private sector, which has led to new and improved sensors being offered by multiple companies; however, most of these sen sors have not been rigorously tested and compared, meaning that it can take many years to design and get funding for an experiment that tests the sensors in a real-world setting, and then run the experiment long enough to get sufficiently representative weather conditions. By the time a research group has undertaken all of these steps it is likely that the sensors being tested will be outdated.
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From page 87... ...
In addition to the need for improved testing of existing environmental sensors, improved sensor technology specific to road weather applications must be developed. In particular, environmental sensors must be robust, reliable, and accurate under a wide variety of weather conditions.
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From page 88... ...
The comparison and testing procedures need to ensure that the results are applicable to a field setting. The committee recommends support for the development of improved sensor technology specific to road weather applications, such as for the amount of ice, all-season precipitation, present weather, and chemical composition of the slurry on the road surface.
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From page 89... ...
One such program is the Meteorological Assimilation Data Ingest System operated by the National Oceanic and Atmospheric Association's (NOAA) Forecast Systems Laboratory.
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From page 90... ...
The committee recommends that the road weather research program take steps to maximize the utility and quality of road weather informa tion. First, to facilitate sharing among multiple entities, the road weather community should help standardize formats of geolocated data and associated metadata (e.g., the National Transportation Communications for Intelligent Transportation System Protocol for Environmental Sensor
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From page 91... ...
. Second, the community should standardize the presentation of road weather information (e.g., in terms of units, colors, or symbols)
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From page 92... ...
Recommendation: Develop observing capabilities to measure the perfor mance of road weather forecasts. The committee recommends that the road weather research program develop special observing facilities to validate forecast tools and verify road weather forecasts.
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From page 93... ...
At night the boundary layer is much shallower. During both day and night, vertical gradients in wind, temperature, and humidity are concentrated near the surface, and observations of atmospheric conditions even 2 to 5 m above the surface may not capture the conditions that affect driving and the road surface.
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From page 94... ...
94 WHERE THE WEATHER MEETS THE ROAD Lee eddy High Density Cushion Low Density a Clearing Screen b FIGURE 4-2 (a) Wind speed reduction in the vicinity of shelter belts with different densities.
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From page 95... ...
The importance of local effects to the roadway environment suggests a two-step approach to simulating road weather conditions: (1) running atmospheric models with land surface data (except for ESS data from stations sited to document nonrepresentative effects)
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From page 96... ...
Clearly this assumption is not always valid because visibility in fog, snow, blowing dust, and other inclement weather conditions, tends to vary greatly over short distances. One possible means of achieving a more representa tive measurement is through analysis of video frames or still images.
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From page 97... ...
facilitate sharing of real-time data and products among entities. Using a GIS-based system, "smart maps" should be created for hazard regions across the country that contain information such as roadways, potential weather-related risks, and weather information.
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From page 98... ...
These indexes can be devel oped locally, for instance, to develop best and worst case budgeting sce narios; or they can be developed for interregional use to compare severity of winter weather conditions. Depending on its purpose, the components of a winter severity index can vary greatly, but the types of variables used fall into the three main categories of geography, solar input, and weather conditions.
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From page 99... ...
For the most part these data, which are collected by traffic operations centers in some states and cities, are used for real-time management of the transportation system but are not archived. There is an opportunity to learn from these data about impacts of weather on traffic flow and to refine estimates of traffic simulation parameters; for example, comparing traffic conditions on days when inclement weather took place with those on fair weather days could help constrain parameters used in traffic simulation models.
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From page 100... ...
· Experience: Time and experience behind the wheel in all types of weather conditions · Familiarity: The extent to which the driver is familiar with the vehicle and roadway characteristics · Memory: The ability to recall previous warnings and appropriate action · Vision: The ability to discriminate highway features, traffic, and weather and roadway conditions · Perception: The way people view the weather conditions, their se verity, and impact · Information processing: The willingness to access available informa tion about driving conditions and the ability to comprehend and respond to information appropriately · Driver response time: The ability to react to changing conditions, warning signs, and weather information · Fatigue: Fatigue adds to an already complex set of circumstances when adverse weather enters the picture
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From page 101... ...
Not well understood are such simple things as reaction to weather information and highway condition messages on highway dynamic message signs and severe weather warnings on the car radio. Additional research is needed to understand how driver behavior changes when new tools or capabilities are made available to them; for instance, do they become overconfident in their ability to drive in inclement weather or do in-vehicle display or communication systems distract the driver?
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From page 102... ...
Road weather research that considers the human factors in driver decision mak ing will help frame the best methods and formats by which information is transmitted to the driving public. ATIS Design Message style Display location Intervening Variables Sensory modality ATIS reliability and availability Trust Self-confidence Acknowledgment accuracy Acknowledgment time Driving Context Situational awareness accuracy Situational awareness confidence Driver Characteristics Mental effort · Age Physical effort · Gender Environmental Characteristics · ATIS reliability and availability · Road sign prevalence Compliance with warnings Driving safety Percent compliance Perceived driving performance Compliance onset Number of crashes Compliance speed Lane tracking Use of turn signals FIGURE 4-5 Factors moderating the effect of ATIS design characteristics on driving safety and warning compliance.
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From page 103... ...
This research should build on the work done by the Advanced Traveler Information System, Commercial Vehicle Operations, and Ad vanced Traffic Management Systems and be compliant with the Na tional ITS Architecture Maintenance and Construction Operations user service bundle. Additional research is needed on effective communica tion of road weather information to traffic managers, maintenance per sonnel, and emergency managers, as they have specialized needs that are significantly different from those of the general public.
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From page 104... ...
The service delivery network includes databases that store infor mation of potential interest to motorists and those that store information about performance and possible maintenance needs downloaded from the vehicle. The service delivery network may also include a workforce to respond individually to driver requests.
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From page 105... ...
MODELING CAPABILITIES AND FORECAST TOOLS Improving modeling capabilities and forecasting tools should be a key objective of a new road weather research program. These efforts should build on existing capabilities in both the meteorology and transportation communities and exploit potential new capabilities (Table 4-2)
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From page 106... ...
Plans include assimilation of very-high-resolution data such as radar. Modeling the One-dimensional Models vertical exchanges of heat and roadway energy-balance models moisture within a vertical column by environment including weather information and road surface properties Multi-dimensional energy Models full three-dimensional energy balance models balance by accounting for the complex terrain of an environment (e.g., vegetation, topography)
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From page 107... ...
· Inherent limits of predictability on the desired time and space scales · Academia · Mesoscale weather predictions · Incomplete or lack of coverage for · National Weather Service specific to a certain region parts of United States local partners · Highway maintenance · Intermittent operations · Private sector decision making · Vulnerable to outages · Can provide initial conditions · Unsteady funding and boundary conditions for road-surface models · Government labs Mesoscale weather prediction · Relatively new model still in · Academia development · U.S. Air Force · Not currently available for routine operations · Development research is ongoing · Academia Predicts the temperature and · Only completely accurate when · Private sector wetness of a roadway surface atmosphere and road surface · Government labs for tactical (< 6 hours)
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From page 108... ...
using weather, flood, traffic, and geographic data to determine best routing and re-routing decisions Decision Support Maintenance Decision Assembles weather conditions of an Systems Support System area, predicts the potential for deteriorating conditions, plans treatment scenarios, and provides decision makers with treatment recommendations High Performance Paving Prediction tool that uses temperature, (HIPERPAV) wind, humidity, and cloud cover information to predict optimum paving windows for roadway construction Coupled End-to-end models that integrate atmospheric-traffic weather and traffic data to simulation models guide decision support scale of a roadway.
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From page 109... ...
, hydrological aspects (e.g., soil infiltration, runoff) , cloud microphysics, and boundary layer physics are parameterized and incorporated into numerical weather prediction models.
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From page 110... ...
Deficiencies in the parameterizations within the numerical weather prediction model are frequently responsible for significant biases in pre dicted parameters especially within the boundary layer, which is the most critical to road weather forecasts. As such, post-processing of model output is often necessary.
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From page 111... ...
Even if road weather models have imperfect parameterizations, accurate and wellplaced road weather information systems will lead to improved forecasts. In the short term, maintaining an accurate, up-to-date database describing road and bridge properties (e.g., composition, structure, depth, roadbed characteristics)
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From page 112... ...
The roadway environment consists of two components: (1) the road surface and (2)
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From page 113... ...
The road weather research program should support development of tailored road weather information products to support real-time opera tions and both near-term tactical (0 to 6 hours) and longer-term strategic (> 6 hours)
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From page 114... ...
The leadership of the road weather research program must support research to determine the best strategy for maximizing predictive skill at minimum cost, this leadership will also have to determine whether a numerical weather prediction model development approach that focuses on down scaling of the conventional mesoscale modeling technology is the correct strategy. Roadway Transportation Models That Account for Weather The transportation community has long recognized the relationship between weather conditions and the operation of the transportation system; however, for many reasons the impacts of weather have generally not been incorporated into the tools used by transportation professionals to evaluate alternative transportation strategies.
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From page 115... ...
Such an initiative would not have been possible 10 years ago because numerical weather prediction and traffic simulation models were not sufficiently mature to be linked efficiently. That is not the case today.
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From page 116... ...
Although both model development paths are fairly mature, there is still much research that is required to tap the opportunities outlined above. Work needs to be done to determine how to best use weather information in traffic simulation models to allow them to further optimize traffic flow for a range of weather conditions in a robust and stable manner.
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From page 117... ...
The use of real-time weather informa tion to support the operation of the transportation system is in its in fancy but should be encouraged; for example, the road maintenance community has made advances in incorporating real-time weather in formation in decision support systems for winter operations. Real-time road weather information would also be useful for warning drivers of dangerous weather conditions and for optimizing commercial vehicle operations.
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From page 118... ...
Some of the needs are as follows. · Integration of weather-based decision support systems with traffic simulation numerical models is required to diagnose and predict traffic flow in urban areas for short periods into the future.
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From page 119... ...
As understanding, modeling sophistication, and computer capabilities al low, such models ultimately could be run in real time to assist in the routine management of the transportation system, thereby enhancing safety, capacity, and traffic flow. COMMUNICATION SUPPORT FOR ROAD WEATHER INFORMATION USERS The road weather research program should support the development of multiple mechanisms for communicating road weather information to a range of users in a manner that supports more informed decision making.
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From page 120... ...
Now, advanced weather decision support systems that assimilate many diverse sources of weather and operational databases have uncertainty metrics as a by-product, and in many ways depend on the metrics for their value to the user, for example, cost analyses can be done effectively by ingesting proba bilistic weather data along with information about available resources and operational status. In addition to developing robust methods for estimating the degree of confidence in road weather information, it is important to devise effective
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From page 121... ...
The road weather research program should support the development of means for estimating the inherent uncertainty in road weather informa tion. Advanced weather decision support systems that assimilate many diverse sources of information need to estimate uncertainty and provide easily understood metrics to aid users in making optimal decisions.
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From page 122... ...
Nevertheless, regular radio remains critical for transmitting weather information to drivers because the costs to consumers are minimal. Cellular communication provides many features that match the needs for communicating weather information to drivers.
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From page 123... ...
Very detailed information about local weather and road conditions, including animated forecasts or other large-bandwidth data, could be transmitted to a vehicle located at a rest stop. As with
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From page 124... ...
Advances in wire less communication hold much promise for providing location-specific weather information to mobile users, but the challenge of determining how best to use these communication technologies remains. INTEGRATING WITH THE EMERGING INFOSTRUCTURE A final but nonetheless critical emphasis of the road weather research program should be to develop a telecommunication infrastructure that takes advantage of new technologies to effectively convey road weather informa tion to end users.
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From page 125... ...
The architecture then provides for the data to be moved to other agencies for processing into useful information. This includes quality assuring the data, analyzing them, generating road weather forecasts from them, and finally packaging and returning all this information to all manner of road transportation users.
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From page 126... ...
Weather and transportation professionals worked together on ITS America's Weather Information Applications Task Force and the FHWA's own Maintenance and Construction Operations (MCO) User Fo rums to develop the MCO User Service.
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