Research Archive

Research Overview

Clarus (which is Latin for "clear") is an initiative to develop and demonstrate an integrated surface transportation weather observing, forecasting and data management system, and to establish a partnership to create a Nationwide Surface Transportation Weather Observing and Forecasting System. The objective of Clarus is to provide information to all transportation managers and users to alleviate the effects of adverse weather (e.g., fatalities, injuries and delays).

The U.S. Department of Transportation (DOT) Federal Highway Administration (FHWA) Road Weather Management Program, in conjunction with the Intelligent Transportation Systems (ITS) Joint Program Office established the Clarus Initiative in 2004 to reduce the impact of adverse weather conditions on surface transportation users.

View Clarus Frequently Asked Questions

Figure 1. The vision for Clarus is to enhance and improve many aspects of surface transportation weather information

image showing Clarus components

Transportation Problem

Adverse weather is associated with over 1.5 million crashes each year, resulting in over 800,000 injuries and 7,400 fatalities. Injuries, loss of life, and property damage cost an average of $42 billion annually. Drivers endure over 500 million hours of delay due to fog, snow, and ice.

Today's weather data is generally insufficient to support transportation operations and safer travel decisions - forecasts are not specific to roadway segments and current data does not characterize roadway conditions. Generally speaking, national and local government agencies provide atmospheric and road weather data and access through multiple means whereas other organizations and the private sector provide applications that use the data and provide them to the public. Yet, increasingly, our transportation and weather systems have been expected to identify weather patterns and provide detailed information about the effects of weather on roadway conditions. Gaining this level of detail and accuracy is a complex but valuable investment, as it can significantly improve the caliber of site-specific, road-condition forecasts for:

  • Drivers, who need accurate and timely alerts to avoid road hazards, leading to fewer weather-related crashes. Driver awareness is a key factor. Road weather applications on handheld devices provide some access, but the access must be easy.
  • Transportation agencies, which require detailed, accurate, segment-specific weather data to anticipate, observe, and manage hazardous conditions. When available, such information will significantly reduce expenses by allowing for targeted decisions on how to allocate labor, minimize use of treatments, and address hazardous areas as a priority.
  • Environmental improvements, with more efficient, spot-specific road-chemical treatments during inclement weather.

Significant challenges exist in moving the industry toward greater levels of specificity:

  • Road weather sensors are individually owned by a variety of organizations: State and local agencies, weather monitoring and reporting agencies, and private sector firms. There is little aggregation, integration, or data exchange to supply the detail needed to support safer travel choices at either broader, regional levels or specific, local levels.
  • Data formats differ across sensor types (environmental, imaging, mobile, and remote), across organizations, and across borders. As a result, it is difficult to check the quality of the data to ensure that it is reliable and timely.
  • Data are typically not readily available to forecasters.
  • Existing data tends to address only general atmospheric conditions rather than specific roadway information.
  • The public does not have sufficient or necessary road weather awareness and tools to be able to access information they can use.

ITS Opportunity

The Clarus Initiative was based on the premise that the integration of a wide variety of weather observing, forecasting,Clarus - Snowy Road photo and data management systems, combined with robust and continuous data quality checking, could serve as the basis for timely, accurate, and reliable weather and road condition information. When disseminated to a wide audience of users, this real-time information would impact decisions by both drivers and transportation operators and alleviate the safety and congestion effects of adverse weather. The Clarus System offered a one-stop, Internet-based portal for all surface transportation environmental observations, allowing users to tap into the system for easy access to the data. Three critical features made Clarus information unique and separate from other forms of weather information available on the market today:

  • Specific to Transportation: Clarus specifically provided information related to roadway conditions.
  • Level of Detail: With the ability to gather data from a vast array of sensors, Clarus enabled service providers to generate and deliver targeted and route-specific information.
  • Quality Control: Clarus performed comprehensive data-quality checks.

Research Goals

The goal of the initiative was to create a robust data assimilation, quality checking, and data dissemination system that could provide near real-time atmospheric and pavement observations from the collective state's investments in road weather information system, environmental sensor stations (ESS) as well as mobile observations from Automated Vehicle Location (AVL) equipped trucks.  The initiative also envisioned utilizing weather data collected from passenger vehicles equipped with transceivers, research that would be conducted under the ITS Joint Program Office’s connected vehicle research initiatives.

Through ongoing Clarus Multi-State Regional Demonstrations, FHWA's Road Weather Management Program objectives were to:

  • Demonstrate that the Clarus System functions as designed by providing incentives to a large number of States, Provinces, and local agencies to contribute data from their Environmental Sensor Station (ESS) networks,
  • Enable proactive transportation system management through utilization of Clarus System data, and
  • Provide an environment for the private sector and academic organizations to innovate and create new and improved services that will benefit the public (both agencies and travelers), academia, and the weather enterprise.

Research Approach

To provide "anytime, anywhere road-weather information," the Clarus Initiative was designed to:

  • Build a coalition of federal agencies responsible for weather forecasting (e.g., the National Oceanic and Atmospheric Administration's [NOAA] National Weather Service [NWS] among others) and private industry, and together design a national network.
  • Create a nationwide surface transportation weather observing and forecasting system by connecting a wide variety of sensors owned and operated by Federal, State, local, and private partners, thereby leveraging the collective investments that agencies have made in road weather information systems.
  • Develop and offer a method for robust data integration, quality checking, and dissemination of road weather observations.
  • Demonstrate and evaluate the ability of the Clarus system to provide near real-time, quality-checked atmospheric and pavement observations.
  • Facilitate access to and effective delivery of road-weather information to a wide audience of customers who require it for a wide range of uses, including truck and fleet logistics planning, daily work commutes and special event planning.

Use Cases

Following Phases I and II of the Clarus System, which consisted of the Proof of Concept and actual development and deployment of the Clarus System, FHWA proceeded with Phase III, a two-year regional demonstration focused specifically on deployment of Clarus-enabled services.   State and Provincial Departments of Transportation teamed-up in response to a solicitation and five “Use Cases” were selected for further development: 

  • Use Case 1: Enhanced Road Weather Forecasting Enabled by Clarus
  • Use Case 2: Seasonal Weight Restriction Decision Support Tool
  • Use Case 3: Non-winter Maintenance and Operations Decision Support Tool
  • Use Case 4: Multi-state Control Strategy Tool
  • Use Case 5: Enhanced Road Weather Content for Traveler Advisories. 

These projects provide for new products and services which would use Clarus data to support and enhance transportation agency operations. Use Case Scenario 1 was focused on scientific/statistical analysis of improvements to surface transportation meteorology & operational forecasting. Use Case Scenario 2-5 focused on improvements to operations, tangible versus intangible benefits (mobility, productivity, safety). All Use Case projects were concluded in 2010 and an independent evaluation of the results was concluded in the spring of 2011.  Following the completion of these Use Cases, the DOT issued a Broad Agency Announcement (BAA) to continue demonstrations of Clarus systems data; eight contracts were awarded as a result to the announcement.

image of a snow plow

Research Findings

To date, the Clarus Initiative has:

  • Worked in partnership with agencies to connect existing sensors into a nationwide network that is now generating and delivering Clarus data.
  • Developed an innovative method for robust data assimilation, quality checking, and data dissemination that can provide near real-time atmospheric and pavement observations from existing technologies.
  • Developed easy, Web-based accessibility to Clarus data through tools such as the Clarus System website.
  • Developed three initial concepts of operation that describe how Clarus data could be used to deliver transportation and weather-related services to support improved operations by public sector agencies. Three multi-State teams comprised of 13 States and three Canadian provinces participated.
  • Conducted proof-of-concept testing to evaluate the ability for data exchange for surface environmental data and relevant surface transportation conditions.

The proof-of-concept testing showed that Clarus was able to aggregate, integrate, and exchange data and provided accurate, quality data. State and local agencies that have connected to Clarus have recognized the benefits and there was growing interest in connecting to Clarus from additional agencies.


Screen Shot from the Clarus System Software

Screen Shot from the Clarus System Software