Due to the dynamic and diverse nature of winter weather and resultant road conditions, WSDOT maintenance personnel use a variety of methods and materials to help prevent snow and ice formation on state highways. Outcomes of snow and ice control treatments will vary, dependent upon severity of winter weather events, topography, traffic levels and speeds, and proximity to support facilities (i.e. liquid chemical storage tanks and salt stockpiles). While outcomes can be measured in a variety of ways, the motoring public most often measures maintenance efforts in terms of road conditions during and immediately after winter weather events. Maintenance personnel also rate roadway conditions during the winter season. This information is used to project expected road conditions associated with snow and ice treatment levels for different events. The unique nature of individual winter weather events limits the relevance of projected expectations on a given storm, but when ratings from an entire winter season are averaged, they become a good indicator of the Level of Service (LOS) provided by maintenance personnel over the entire season. Winter climates differ greatly between Eastern and Western Washington, so road treatment levels may vary on either side of the Cascades to match the ability to respond to those conditions. Limited funding also requires prioritization of roads for snow and ice control, so that different levels of service will be employed for individual roads and sections of roads