For years, State Departments of Transportation (DOTs) have invested in thousands of Environmental Sensor Stations (ESS) along roadway rights-of-way, primarily in support of winter maintenance activities. Most ESS, which are field components of Road Weather Information Systems (RWIS), have one or more sensors to measure atmospheric, pavement or water level conditions.

While RWIS have become an integral part of winter maintenance operations, the ability to fully utilize these data for other applications are often hampered by suboptimal system design. For example, there are no standards for ESS data reporting formats, communication protocols or instrument siting. There is no uniformity in communication polling frequencies or data quality control. These conditions limit the utilization of these valuable data not only for DOT activities but also for use in the greater meteorological and transportation communities.

The U.S. DOT Federal Highway Administration (FHWA) Road Weather Management program, in conjunction with the Intelligent Transportation Systems Joint Program Office, recognized that disparate state investments could be better utilized if they were standardized and made available from one location. In addition, emerging data sources such as vehicles could lead to a dramatic increase in the number of observations at the surface. In parallel with the FHWA work, the publication of the National Academy of Sciences’ Board on Atmospheric Science and Climate report, “Where the Weather Meets the Road: A Research Agenda for Improving Road Weather Services” clearly articulated the need for a robust, integrated observational network and data management system. The FHWA responded with a new initiative called “Clarus” – the Nationwide Surface Transportation Weather Observing and Forecasting System.

The objective of Clarus is to reduce the impact of adverse weather for all road and transit users and operators by designing and demonstrating an integrated road weather observational, forecasting and data management system, and developing a partnership to establish a nationwide road weather observation network. This paper and presentation will describe the Clarus program, its implementation phases and associated research agenda.