# The FHWA Clarus Initiative: The Nationwide Surface Transportation Weather Observing and Forecasting System {#the-fhwa-clarus-initiative-the-nationwide-surface-transportation-weather-observing-and-forecasting-system .unnumbered}

Paul A. Pisano, James S. Pol, Roemer M. Alfelor, Lynette C. Goodwin, and
Andrew D. Stern

#  {#section .unnumbered}

**Abstract.** Transportation managers use data from Environmental Sensor
Stations (ESS) to support a wide range of operational decisions. In
addition, transportation mangers and road users rely on a wide variety
of tailored road weather information products (based on these sensor
observations) to make safer and more efficient decisions. The Federal
Highway Administration and the U.S. DOT began a five-year initiative
called Clarus, the Nationwide Surface Transportation Weather Observing
and Forecasting System, to improve operations and enhance these road
weather information products by collecting all ESS data from existing
observing networks. Clarus data will be assimilated, quality-controlled,
and made available to a broad range of users through an Internet portal.
The Clarus initiative will also contribute to technological advances and
promote interfederal cooperation. The evolving discipline of
weather-responsive traffic management strategies will depend on timely,
accurate, and relevant observations and forecasts made possible through
Clarus.

# INTRODUCTION {#introduction .unnumbered}

# Weather events can cause slick pavement, lower traffic speeds, increase speed variability, reduce roadway capacity, increase delay, escalate crash risk, disrupt access to roads (e.g., lane obstruction, flooding), and damage road infrastructure (e.g., pavement buckling, traffic control device failure). To mitigate these effects, road operating and maintenance agencies need road weather observations, forecasts, and decision support tools. As demonstrated with the winter maintenance community, general weather information products do not satisfy the specific requirements of these agencies and surface transportation-specific services are needed. {#weather-events-can-cause-slick-pavement-lower-traffic-speeds-increase-speed-variability-reduce-roadway-capacity-increase-delay-escalate-crash-risk-disrupt-access-to-roads-e.g.-lane-obstruction-flooding-and-damage-road-infrastructure-e.g.-pavement-buckling-traffic-control-device-failure.-to-mitigate-these-effects-road-operating-and-maintenance-agencies-need-road-weather-observations-forecasts-and-decision-support-tools.-as-demonstrated-with-the-winter-maintenance-community-general-weather-information-products-do-not-satisfy-the-specific-requirements-of-these-agencies-and-surface-transportation-specific-services-are-needed. .unnumbered}

#  {#section-1 .unnumbered}

# Transportation managers use data from Environmental Sensor Stations (ESS)---most of which are field components of Road Weather Information Systems (RWIS)---to support their operational decisions, improve traffic flow, and ensure road safety. State transportation agencies have deployed over 2,100 ESS along roadways to provide managers with weather, pavement condition, and water level data. Additional sensors are owned and operated by local transportation agencies. However, under current operating conditions, ESS data are not managed to develop a comprehensive picture of road weather conditions regionally or nationwide. State agency ESS are furnished by several vendors and provide data in different formats at varying levels of quality. Central RWIS utilize various communication protocols, polling frequencies, and user interfaces. Further, transportation agencies have limited observation data sharing capabilities. These sub-optimal implementations hamper the use of the data, and limit the ability of national information service providers to provide consistent products. In other words, these factors have prevented existing road weather observing networks from being leveraged for 21st century operations. {#transportation-managers-use-data-from-environmental-sensor-stations-essmost-of-which-are-field-components-of-road-weather-information-systems-rwisto-support-their-operational-decisions-improve-traffic-flow-and-ensure-road-safety.-state-transportation-agencies-have-deployed-over-2100-ess-along-roadways-to-provide-managers-with-weather-pavement-condition-and-water-level-data.-additional-sensors-are-owned-and-operated-by-local-transportation-agencies.-however-under-current-operating-conditions-ess-data-are-not-managed-to-develop-a-comprehensive-picture-of-road-weather-conditions-regionally-or-nationwide.-state-agency-ess-are-furnished-by-several-vendors-and-provide-data-in-different-formats-at-varying-levels-of-quality.-central-rwis-utilize-various-communication-protocols-polling-frequencies-and-user-interfaces.-further-transportation-agencies-have-limited-observation-data-sharing-capabilities.-these-sub-optimal-implementations-hamper-the-use-of-the-data-and-limit-the-ability-of-national-information-service-providers-to-provide-consistent-products.-in-other-words-these-factors-have-prevented-existing-road-weather-observing-networks-from-being-leveraged-for-21st-century-operations. .unnumbered}

#  {#section-2 .unnumbered}

# In a joint effort, the Federal Highway Administration (FHWA) Road Weather Management Program and the U.S. Department of Transportation (DOT) Intelligent Transportation Systems (ITS) Joint Program Office began a five-year initiative called Clarus, the Nationwide Surface Transportation Weather Observing and Forecasting System. Clarus---which is Latin for "clear"---will bring together public investments in ESS to reduce the impact of adverse weather for all road and transit users and operators. The Clarus initiative will demonstrate a regional road weather observing, forecasting, and data management system as well as establish a partnership for a nationwide system.  {#in-a-joint-effort-the-federal-highway-administration-fhwa-road-weather-management-program-and-the-u.s.-department-of-transportation-dot-intelligent-transportation-systems-its-joint-program-office-began-a-five-year-initiative-called-clarus-the-nationwide-surface-transportation-weather-observing-and-forecasting-system.-claruswhich-is-latin-for-clearwill-bring-together-public-investments-in-ess-to-reduce-the-impact-of-adverse-weather-for-all-road-and-transit-users-and-operators.-the-clarus-initiative-will-demonstrate-a-regional-road-weather-observing-forecasting-and-data-management-system-as-well-as-establish-a-partnership-for-a-nationwide-system. .unnumbered}

#  {#section-3 .unnumbered}

######## WHAT ARE THE POTENTIAL BENEFITS OF CLARUS? {#what-are-the-potential-benefits-of-clarus .unnumbered}

#  {#section-4 .unnumbered}

# The Clarus initiative will contribute to technological and institutional advances, ultimately leading to a safer and more efficient surface transportation system. With respect to institutional advances, the initiative will promote inter-federal cooperation. By providing one-stop access to road weather data, Clarus will contribute to national environmental data integration efforts and enhance relationships between federal agencies such as the U.S. DOT, FHWA, the Office of the Federal Coordinator for Meteorology, the National Oceanic and Atmospheric Administration (NOAA), and the National Weather Service. FHWA and NOAA have taken steps toward a partnership to achieve their shared goals for a safer, more efficient surface transportation system. By working together these agencies will improve surface transportation weather and road condition products and services to enable transportation users and operators to make effective and efficient decisions during adverse weather.  {#the-clarus-initiative-will-contribute-to-technological-and-institutional-advances-ultimately-leading-to-a-safer-and-more-efficient-surface-transportation-system.-with-respect-to-institutional-advances-the-initiative-will-promote-inter-federal-cooperation.-by-providing-one-stop-access-to-road-weather-data-clarus-will-contribute-to-national-environmental-data-integration-efforts-and-enhance-relationships-between-federal-agencies-such-as-the-u.s.-dot-fhwa-the-office-of-the-federal-coordinator-for-meteorology-the-national-oceanic-and-atmospheric-administration-noaa-and-the-national-weather-service.-fhwa-and-noaa-have-taken-steps-toward-a-partnership-to-achieve-their-shared-goals-for-a-safer-more-efficient-surface-transportation-system.-by-working-together-these-agencies-will-improve-surface-transportation-weather-and-road-condition-products-and-services-to-enable-transportation-users-and-operators-to-make-effective-and-efficient-decisions-during-adverse-weather. .unnumbered}

#  {#section-5 .unnumbered}

# With respect to technological advances, resources will be devoted to research in fixed, mobile, and remote environmental sensors such as Closed Circuit Television (CCTV) cameras to measure driver level visibility, vehicle-mounted sensors deployed as part of the Vehicle Infrastructure Integration (VII) initiative, and short-range low-power radar to provide better information on the lower atmosphere. Clarus will also benefit surface transportation agencies by providing timely, accurate, and relevant road weather observations through an Internet portal. Integrated, quality-controlled observation data will be provided through a feedback mechanism to alert agencies of suspect, missing, or erroneous data. Clarus will allow access to observation data and metadata in a common format. This standardized source of observation data will enhance market opportunities for the private sector and foster development of more precise forecast and decision support products for public transportation agencies.![](media/image1.wmf){width="3.4631944444444445in" height="2.425in"} {#with-respect-to-technological-advances-resources-will-be-devoted-to-research-in-fixed-mobile-and-remote-environmental-sensors-such-as-closed-circuit-television-cctv-cameras-to-measure-driver-level-visibility-vehicle-mounted-sensors-deployed-as-part-of-the-vehicle-infrastructure-integration-vii-initiative-and-short-range-low-power-radar-to-provide-better-information-on-the-lower-atmosphere.-clarus-will-also-benefit-surface-transportation-agencies-by-providing-timely-accurate-and-relevant-road-weather-observations-through-an-internet-portal.-integrated-quality-controlled-observation-data-will-be-provided-through-a-feedback-mechanism-to-alert-agencies-of-suspect-missing-or-erroneous-data.-clarus-will-allow-access-to-observation-data-and-metadata-in-a-common-format.-this-standardized-source-of-observation-data-will-enhance-market-opportunities-for-the-private-sector-and-foster-development-of-more-precise-forecast-and-decision-support-products-for-public-transportation-agencies. .unnumbered}

# As shown in Figure 1, ESS data available through Clarus will support a broad range of users including traffic managers, maintenance managers, transit and rail operators, information service providers, emergency managers, law enforcement, forecasters (e.g., NOAA and private vendors), and other agencies including the Department of Agriculture and the Department of Homeland Security. {#as-shown-in-figure-1-ess-data-available-through-clarus-will-support-a-broad-range-of-users-including-traffic-managers-maintenance-managers-transit-and-rail-operators-information-service-providers-emergency-managers-law-enforcement-forecasters-e.g.-noaa-and-private-vendors-and-other-agencies-including-the-department-of-agriculture-and-the-department-of-homeland-security. .unnumbered}

# Clarus data can be integrated with Advanced Traffic Management Systems (ATMS), Emergency Management Systems (EMS), Advanced Traveler Information Systems (ATIS), and other systems to help managers mitigate weather effects on safety, mobility, and productivity. Armed with Clarus data and the improved products it enables, managers can reduce crash frequency, better manage congestion, and minimize operating costs using three types of road weather management strategies---Advisory, Control, and Treatment strategies---as described below. {#clarus-data-can-be-integrated-with-advanced-traffic-management-systems-atms-emergency-management-systems-ems-advanced-traveler-information-systems-atis-and-other-systems-to-help-managers-mitigate-weather-effects-on-safety-mobility-and-productivity.-armed-with-clarus-data-and-the-improved-products-it-enables-managers-can-reduce-crash-frequency-better-manage-congestion-and-minimize-operating-costs-using-three-types-of-road-weather-management-strategiesadvisory-control-and-treatment-strategiesas-described-below. .unnumbered}

# [Advisory strategies]{.underline} provide information on prevailing and predicted conditions to the traveling public. Strategies include posting warnings on Dynamic Message Signs (DMS), broadcasting messages via Highway Advisory Radio (HAR), and providing route-specific road condition reports through agency web sites and interactive telephone systems (e.g., 511). [Control strategies]{.underline} alter the state of roadway devices to permit or restrict traffic flow and regulate roadway capacity. Examples include weather-related signal timing; variable speed limits based upon visibility and pavement conditions; bridge, lane, and road closures; and restrictions on designated vehicles (e.g., tractor trailers in high wind conditions, cars without snow chains). A successful control strategy is described in the box.  {#advisory-strategies-provide-information-on-prevailing-and-predicted-conditions-to-the-traveling-public.-strategies-include-posting-warnings-on-dynamic-message-signs-dms-broadcasting-messages-via-highway-advisory-radio-har-and-providing-route-specific-road-condition-reports-through-agency-web-sites-and-interactive-telephone-systems-e.g.-511.-control-strategies-alter-the-state-of-roadway-devices-to-permit-or-restrict-traffic-flow-and-regulate-roadway-capacity.-examples-include-weather-related-signal-timing-variable-speed-limits-based-upon-visibility-and-pavement-conditions-bridge-lane-and-road-closures-and-restrictions-on-designated-vehicles-e.g.-tractor-trailers-in-high-wind-conditions-cars-without-snow-chains.-a-successful-control-strategy-is-described-in-the-box. .unnumbered}

#  {#section-6 .unnumbered}

# [Treatment strategies]{.underline} supply resources, such as salt and sand, to roadways to minimize or eliminate weather impacts. Anti-icing and fog dispersal are examples of treatment strategies. Advisory, control and treatment strategies have been documented in "Best Practices for Road Weather Management, Version 2.0". This resource contains case studies from every region of the country, a listing of road weather publications, and an overview of environmental sensor technologies. The resource is available on the Road Weather Management Program web site (www.fhwa.dot.gov/weather).  {#treatment-strategies-supply-resources-such-as-salt-and-sand-to-roadways-to-minimize-or-eliminate-weather-impacts.-anti-icing-and-fog-dispersal-are-examples-of-treatment-strategies.-advisory-control-and-treatment-strategies-have-been-documented-in-best-practices-for-road-weather-management-version-2.0.-this-resource-contains-case-studies-from-every-region-of-the-country-a-listing-of-road-weather-publications-and-an-overview-of-environmental-sensor-technologies.-the-resource-is-available-on-the-road-weather-management-program-web-site-www.fhwa.dot.govweather. .unnumbered}

#  {#section-7 .unnumbered}

The evolving discipline of weather-responsive traffic management
strategies will depend on better observations and forecasts of weather,
pavement, and water level conditions. In this case "better" means
route-specific road weather data at high resolution comparable in scale
to road network databases. Integration of Clarus data with ATMS could
provide managers with tailored decision support based on the unique
configuration, characteristics, and microclimatology of an urban road
network. For example, Clarus data and information could be used to track
the location and movement of weather fronts or storm cells and the onset
of precipitation or strong winds. Such dynamic assessments could result
in targeted operational decisions and lead to development of new and
improved management strategies. New opportunities for controlling
traffic flow and advising travelers in adverse weather will emerge with
better road weather data sharing, analysis, and integration capabilities
made possible through Clarus.

######## CLARUS SYSTEM DESIGN CHALLENGES  {#clarus-system-design-challenges .unnumbered}

#  {#section-8 .unnumbered}

Design documents for an open, extensible Clarus system are being
developed using a systems engineering approach that begins with
determination of high level system requirements. These high level
requirements are based on a Concept of Operations that describes the
operational needs of users, the behavior of the Clarus system, as well
as system interfaces and boundaries. The Concept of Operations addresses
the following questions related to the operation of the Clarus system:
**What are Clarus user needs (and corresponding road weather information
requirements) for safer and more effective decision making as it affects
transportation operations? What data exchange requirements must be
satisfied to support user decisions? How will institutional structures
affect the Clarus system design?**

**Information Requirements**

#  {#section-9 .unnumbered}

The Concept of Operations describes user information requirements in
functional scenarios for various user groups based upon their specific
operational responsibilities and expectations. The Clarus system design
must accommodate numerous, disparate functions. Information requirements
for the traffic operations function, traveler information function, and
NOAA function are discussed below. Other functions in the Concept of
Operations include roadway maintenance, transit management, public
safety, railroad operations, and commercial vehicle operations.
Additional functions will be defined as high resolution data sets evolve
and new data applications are developed.

In the traffic operations function, data from fixed ESS and
vehicle-based sensors will be integrated with weather information from
other sources. The integrated data will be used in quality control
algorithms to flag suspect data, which will be sent back to agencies
providing the data. Quality-controlled data will then be transferred to
surface transportation weather information service providers (e.g.,
DOTs, private vendors) who will add value and provide road weather
observations, forecasts, and decision support tools to traffic operation
centers. This value-added data enabled through Clarus will give traffic
operations personnel a better picture of weather effects on roadway
conditions, traffic flow, and crash risk across a region. A depiction of
the traffic operations function is shown in Figure 2.

In the traveler information function, the data flows are similar to
those in Figure 2, with a focus on surface transportation weather
information service providers, who will use Clarus data to provide more
comprehensive environmental information to travelers. Customized road
weather advisories could be delivered to the public to influence their
travel decisions (e.g., travel mode, route choice, trip deferral,
departure time, driver behavior). Targeted road weather information
delivered through roadway warning systems, interactive telephone
systems, in-vehicle devices, Personal Digital Assistants (PDAs), and
kiosks could improve safety and
mobility.![](media/image2.wmf){width="6.497916666666667in"
height="4.116666666666666in"}

The NOAA functional scenario describes interactions between the Clarus
system and NOAA. NOAA is the federal government agency that collects
weather and hydrologic information, performs numerical modeling and
hydro-meteorological research, and provides hydro-meteorological warning
and forecast services. NOAA products and services are used by the media,
the general public, government agencies, the military, and the private
weather information community. Products and services for all of these
users will be enhanced by the integration of Clarus data with NOAA
assets.

Designing the Clarus system to serve such a diverse group of users poses
several questions: **How can the range of user information requirements
be most thoroughly captured? What will be needed to ensure that new data
sets, innovative data applications, and future technologies can be
incorporated into the Clarus system? How will designers add new user
functions as the system evolves? What types of information delivery
mechanisms will be needed for each user group?**

**Data Exchange Requirements**

#  {#section-10 .unnumbered}

In addition to describing what types of data are needed for various
functions, the Concept of Operations also addresses how frequently data
are needed. Road weather information must correspond to the appropriate
time horizon to support different types and sequences of management
decisions. In Table 1, the coordinated decision scales from planning to
warning represent a hierarchy from managers, to dispatch and operations
staff, to remote devices controlled by operators to warn motorists or
regulate road usage.

**Table 1 --** Road Weather Information and Management Decisions

+--------+---------+-------+------------------------------------------+
| **W    | **D     | *     | **Management Function**                  |
| eather | ecision | *Time |                                          |
| Sc     | S       | Hori  | **Examples**                             |
| ales** | cales** | zon** |                                          |
+--------+---------+-------+------------------------------------------+
| Cl     | P       | M     | -   Design facilities and systems        |
| imatic | lanning | onths |                                          |
| Scale  |         | to    | -   Procure resources (e.g., hire/train  |
|        |         | Years |     staff, buy equipment)                |
|        |         |       |                                          |
|        |         |       | -   Coordinate with adjacent states      |
+--------+---------+-------+------------------------------------------+
| Sy     | Oper    | Hours | -   Identify threatened roads and        |
| noptic | ational | to    |     populations                          |
| Scale  |         | Days  |                                          |
|        |         |       | -   Consider mitigation strategy         |
|        |         |       |     alternatives                         |
|        |         |       |                                          |
|        |         |       | -   Manage resource deployment (e.g.,    |
|        |         |       |     call in maintenance crews)           |
+--------+---------+-------+------------------------------------------+
| Meso   | Oper    | Mi    | -   Select mitigation strategies (e.g.,  |
| -scale | ational | nutes |     advise, control, treat)              |
|        |         | to    |                                          |
|        |         | Hours | -   Control traffic flow (e.g., reduce   |
|        |         |       |     speed limit, close road)             |
|        |         |       |                                          |
|        |         |       | -   Treat roads, bridges, ramps (e.g.,   |
|        |         |       |     apply chemicals, plow)               |
+--------+---------+-------+------------------------------------------+
| Micro  | Warning | Se    | -   Activate warning systems (e.g., DMS, |
| -scale |         | conds |     flashing beacons)                    |
|        |         | to    |                                          |
|        |         | Mi    | -   Post travel conditions and           |
|        |         | nutes |     restrictions on web site             |
|        |         |       |                                          |
|        |         |       | -   Broadcast road weather conditions    |
|        |         |       |     (e.g., HAR, 511)                     |
+--------+---------+-------+------------------------------------------+

Data exchange requirements will affect the design of the Clarus system.
The system must be flexible and sensitive enough to provide data for the
warning decision scale (i.e., real-time and near real-time). Designers
will have to ask themselves several critical questions. **What are the
minimum data latency requirements? How will stringent latency
requirements affect the open system design process? How will latency
requirements impact data quality (e.g., timeliness, accuracy)? Can
latency requirements be satisfied with different levels of quality
control?**

**Institutional Issues**

#  {#section-11 .unnumbered}

In order for the Clarus system to benefit transportation and weather
information communities, several institutional barriers must be
overcome. Some data owners limit public distribution of specific
observation and forecast parameters. The concern is that such
restrictions minimize their liability exposure by controlling release of
data that may be inaccurate or unreliable. There is also concern about
sharing information (e.g., road temperature profiles) with communities
that may not understand it. Some private providers have instituted
policies that deem data as proprietary, preventing its public
distribution. Other data providers have contracts that either restrict
data distribution or require a license for its use.

These and other institutional issues, which will influence how public
and private entities interact with the Clarus system, must be considered
as system design documents are created. **What types of distribution
options and agreements will be needed to encourage public transportation
agencies to share data with Clarus? How do we strike a balance between
the responsibilities of the public agencies and the opportunities of the
private sector?** **How will the Clarus system manage data distribution
to serve both transportation and weather information stakeholders?**

# CONCLUSION  {#conclusion .unnumbered}

#  {#section-12 .unnumbered}

The Clarus initiative will combine systems engineering techniques,
network and software design, emerging technology research, and
increasingly complex field demonstrations to develop and establish an
advanced road weather observing network. Ultimately, the Clarus
initiative will lead to collaboration and resource sharing by public and
private sectors across the surface transportation and weather
information communities. One-stop access to quality-controlled Clarus
data will stimulate creation of new observational products and foster
development of more accurate, route-specific road weather forecast and
decision support applications. Road operating and maintenance agencies
will be able to use these new products to enhance or develop innovative
mitigation strategies that improve safety, mobility, and productivity
across the nation.

# As described above, a number of outstanding questions still need to be resolved in order to achieve these goals. The questions include the following: {#as-described-above-a-number-of-outstanding-questions-still-need-to-be-resolved-in-order-to-achieve-these-goals.-the-questions-include-the-following .unnumbered}

**User Needs and Information Requirements**

# What are Clarus user needs (and corresponding road weather information requirements) for safer and more effective decision making as it affects transportation operations? 

# How can the range of user information requirements be most thoroughly captured? 

# What will be needed to ensure that new data sets, innovative data applications, and future technologies can be incorporated into the Clarus system?

# How will designers add new user functions as the system evolves? 

# What types of information delivery mechanisms will be needed for each user group? 

#  {#section-13 .unnumbered}

**Data Exchange Requirements**

# What data exchange requirements must be satisfied to support user decisions? 

# What are the minimum data latency requirements?

# How will stringent latency requirements affect the open system design process? 

# How will latency requirements impact data quality (e.g., timeliness, accuracy)?

# Can latency requirements be satisfied with different levels of quality control?

#  {#section-14 .unnumbered}

**Institutional Issues & Challenges**

# How will institutional structures affect the Clarus system design?

# What types of distribution options and agreements will be needed to encourage public transportation agencies to share data with Clarus?

# How do we strike a balance between the responsibilities of the public agencies and the opportunities of the private sector? 

# How will the Clarus system manage data distribution to serve both transportation and weather information stakeholders? 

#  {#section-15 .unnumbered}

# In summary, these questions revolve around technological issues, such as system design, and institutional challenges. The initiative managers have engaged stakeholders through the Clarus Initiative Coordinating Committee (ICC) as a means of addressing these questions. The initiative managers and the ICC, which is composed of members from transportation and weather communities, are working together to resolve these critical questions.  {#in-summary-these-questions-revolve-around-technological-issues-such-as-system-design-and-institutional-challenges.-the-initiative-managers-have-engaged-stakeholders-through-the-clarus-initiative-coordinating-committee-icc-as-a-means-of-addressing-these-questions.-the-initiative-managers-and-the-icc-which-is-composed-of-members-from-transportation-and-weather-communities-are-working-together-to-resolve-these-critical-questions. .unnumbered}

# REFERENCES {#references .unnumbered}

#  {#section-16 .unnumbered}

1.  FHWA Road Weather Management Program, "Weather Information for
    Roadway Transportation: Preliminary Data Gap Analysis," prepared for
    the OFCM Committee for Integrated Observing Systems, May 2004.

2.  Goodwin, L., "Best Practices for Road Weather Management," Version
    2.0, prepared by Mitretek Systems for the FHWA Road Weather
    Management Program, FHWA-OP-03-081, May 2003,
    www.ops.fhwa.dot.gov/weather/best_practices/CaseStudiesFINALv2-RPT.pdf.

3.  Iteris and Meridian, "Clarus: Draft Concept of Operations," prepared
    for the FHWA, December 2004, www.clarusinitiative.org/conops.htm.

4.  ITS America, "Clarus Initiative Web Site," December 2004,
    www.clarusinitiative.org.

5.  National Research Council, "Where the Weather Meets the Road: A
    Research Agenda for Improving Road Weather Services," National
    Academies Press, April 2004, www.nap.edu/catalog/10893.html.

6.  Pisano, P. and Goodwin, L., "Research Needs for Weather-Responsive
    Traffic Management," presented at the 2004 Annual Meeting of the
    Transportation Research Board, January 2004,
    www.ops.fhwa.dot.gov/weather/best_practices/WxRspTfcMgmtTRB2004.pdf.

7.  Pisano, P., et al, "Clarus -- the Nationwide Surface Transportation
    Weather Observing and Forecasting System," presented at the 2005
    Annual Meeting of the Transportation Research Board, January 2005.

8.  U.S. DOT, "ITS Joint Program Office Web Site," December 2004,
    www.its.dot.gov.

**[Authors' Information:]{.underline}**

Paul A. Pisano

Team Leader

Road Weather Management Program

FHWA, Office of Transportation Operations

400 7^th^ Street, S.W.

Washington, DC 20590

Phone: 202-366-1301

Email: paul.pisano@fhwa.dot.gov

James S. Pol

Transportation Specialist

ITS Joint Program Office

Federal Highway Administration

400 7^th^ Street, S.W.

Washington, D.C. 20590

Phone: 202-366-4374

Email: james.pol@fhwa.dot.gov

Roemer M. Alfelor

Transportation Specialist

Road Weather Management Program

FHWA, Office of Transportation Operations

400 7^th^ Street, S.W.

Washington, DC 20590

Phone: 202-366-9242

Email: roemer.alfelor@fhwa.dot.gov

Lynette C. Goodwin

Lead Transportation Engineer

Intelligent Transportation Systems Division

Mitretek Systems, Inc.

600 Maryland Avenue, Suite 755

Washington, DC 20024

Phone: 202-488-3033

Email: lynette.goodwin@mitretek.org

Andrew D. Stern

Meteorologist

Oceanic, Atmospheric and Space Systems

Mitretek Systems, Inc.

3150 Fairview Park Drive South

Falls Church, Virginia 22042

Phone: 703-610-1754

Email: astern@mitretek.org