Decision support weather information for maintenance personnel

S. Edward Boselly
Road Weather Program Manager
Washington State Department of Transportation
Olympia, Washington

Weather impacts nearly all highway maintenance activities. Consequently, maintenance managers and operators need accurate and reliable weather information to manage their resources effectively and efficiently. These decision makers also need weather information presented in a user-friendly manner so that they are not forced to try to integrate information from many sources in order to make their decisions.

Under contract to the Washington State Department of Transportation (WSDOT), researchers at the University of Washington (UW) developed a capability to gather data from the many networks of weather instrumentation around the state. They integrated these data into a user-friendly format and developed a website for data display. The data appear on the WSDOT Traffic and Weather web page. Unfortunately, the website doesn't provide key road-related forecast information needed by decision makers.

  Figure 1. ARROWS statewide view.

The UW researchers, in response to WSDOT input, developed a new product for maintenance operations decision-making. This product, called the Automated Real-time ROad Weather System (ARROWS), takes numerical weather prediction output and presents the forecast information in a format for easy use and understanding by maintenance personnel. The UW provided access to the original version of ARROWS to key volunteers in WSDOT maintenance over the summer of 2003 for review and assistance in the development. The UW released the final development version of ARROWS for a formal evaluation in the fall of 2003.

Thanks to a regional meteorological modeling consortium pooled fund effort, the UW runs high-resolution models based on output from an ensemble of eight national and international global models. Research indicates that the average of all of the ensemble members tends to provide the best forecast. The UW takes this ensemble mean and generates forecasts down to 4 km resolution. They then use this high-resolution model output to initialize and run a land surface model. This surface output generates pavement temperature forecasts for 24 hours for all state highways in six four-hour increments. The output also includes graphical and text forecasts of air temperature, dew point, and precipitation in one-hour increments for points about 10 km apart on all the state highways.

Figure 2. ARROWS detailed view showing roadway forecast locations and a 24-hour forecast.

ARROWS also generates warnings based on the forecasts. When a decision maker logs on to ARROWS, exclamation point icons appear on the forecast time slot bar to indicate that warnings exist during a six-hour time increment. In the warning mode, the ARROWS map will then display a graphic in the Maintenance Region where a warning is in effect in that time period. The graphic indicates the type of warning, for instance snow, frost, etc. In Regional or shed views, green dots appear along the highways. These dots represent forecast points. If a warning exists for any one of these locations, the dots appear red. Maintenance managers can look at the next 24 hours and determine if they need to be worried about weather at specific locations. By clicking on a dot, the user gets a 24-hour forecast for that location. The graphic will also indicate if there are any warnings in the vicinity of that location by milepost.

ARROWS is nearly one-stop shopping for weather information. ARROWS provides color-coded map displays for forecasts of precipitation, the statewide road network color-coded for pavement temperature, air temperature and wind forecast. The UW created for the ARROWS display a composite statewide radar product with a three-plus hour looping capability. ARROWS also contains links to other weather information, such as the National Weather Service, the Northwest Weather and Avalanche Center, and any vendor that is under contract to provide weather forecasting services.

Most maintenance personnel who used ARROWS liked it. The development continues to be a dynamic process. WSDOT and the UW worked interactively during the 2003-2004 winter demonstration. The UW changed and upgraded the ARROWS presentations based on feedback from field users. At the end of the winter season a survey obtained additional input for improving ARROWS. Suggestions included adding additional links and deleting unused ones. They requested forecasts be extended to at least 36 hours. The UW is working to revamp the forecasting process to accommodate this extension. Finally, and perhaps most importantly, most users indicated that ARROWS helped them perform their work more effectively and efficiently, and more than 90 percent indicated that the development of ARROWS should continue. ARROWS will again be evaluated during the 2004-2005 winter.

S. Edward Boselly can be reached at (360) 705-7863 or at For a PowerPoint(r) presentation on ARROWS, go to