Best Practices for Road Weather Management. Version 3.0

On average, there are over 6,301,000 vehicle crashes each year. Twenty-four percent of these crashes – approximately 1,511,000 – are weather-related, resulting in 7,130 fatalities and 629,000 injuries. In spite of these statistics, there is a perception that transportation managers can do little about weather. However, three types of mitigation measures may be employed in response to environmental threats: advisory; control; and treatment strategies. Advisory strategies provide information on prevailing and predicted conditions to both transportation managers and motorists. Control strategies alter the state of roadway devices to permit or restrict traffic flow and regulate roadway capacity. Treatment strategies supply resources to roadways to minimize or eliminate weather impacts. Many treatment strategies involve coordination of traffic, maintenance, and emergency management agencies. These road weather management strategies are employed in response to various weather threats including fog, high winds, snow, rain, ice, flooding, tornadoes, hurricanes, and avalanches. This report contains 27 case studies of systems in 22 states that improve roadway operations under inclement weather conditions. Each case study has six sections including a general description of the system, system components, operational procedures, resulting transportation outcomes, implementation issues, as well as contact information and references.