The Arizona Department of Transportation (ADOT) is responsible for snow and ice control on state-designated highways in Northern Arizona. The processes and procedures for winter maintenance have evolved from the early days of snow removal only. These procedures sometimes prevent adequate mobility of the motoring public during winter storms or result in road closures because of snow or ice problems on the roads. In 1997, ADOT contracted with a team of snow- and ice-control experts to review existing practices and procedures and to make recommendations to improve snow and ice control. The review process included investigating ADOT's use of weather information, the location of Road Weather Information System (RWIS) sites and plans for new sites, existing resources and procedures for snow and ice control, maintenance of RWIS and snow- and ice-control equipment, and training of personnel. The original statement of the research problem and its objective are presented, the research findings are summarized, and recommendations delivered to ADOT, designed to improve snow and ice control in Northern Arizona, are documented. Attention was given throughout the analysis and subsequent recommendations to the special need for snow and ice control in the transition zone, the region between the desert valley and the high country of Arizona.