Winter Weather Events, Crashes and Traffic Impacts: Applying Environmental Communication Strategies to Winter Weather Messaging
Randy Graham, National Weather Service, Salt Lake City, UT
Jeff Williams, Utah Department of Transportation

Weather events have a significant impact on traffic flow as well as traveler safety.  In the period between 2002 and 2012, approximately 23 percent of crashes in the United Sates were weather-related. This translates into yearly weather-related averages of over 6,253 people killed, over 480,000 injured, and almost 1 million people involved in property damage only (no injuries or fatalities) crashes. In the Salt Lake City, UT metropolitan area, recurring traffic congestion (i.e., primary commute times) and non-recurring congestion (weather events) result in an estimated average annual cost of $449 million.


The National Weather Service issues forecasts, including watches, warnings and advisories to help individuals make the best decisions possible and to modify their behavior, when appropriate. However, traditional communication strategies, in the form of preparedness calls to action do not leverage proven risk communication strategies. Strategies such as the use of odds ratios and normative messages have been shown to be effective and increase the likelihood that an individual will change their behavior. Such messages could promote increased driver behavior modification, such as an individual delaying their commute or traveling via an alternate route.  These message strategies present an opportunity for the National Weather Service and the Utah Department of Transportation to improve communication and service to the traveling public.

The Utah Department of Transportation (UDOT) has a world-class network of road sensors which monitor traffic flow (speed), the number of vehicle miles traveled, delays, and lost productivity due to congestion. In addition, UDOT has road sensors which measure the road surface temperature, freezing point of the road surface (which can be sub-freezing due to proactive mitigation), and soil temperature.  This traffic and road sensor data will be correlated with weather events and crash data in the Salt Lake City area for the winters of 2013-14 through 2015-16. This will result in quantifiable impacts associated with storm severity and timing as well as associated road surface information. This impact information will then be leveraged to create more effective messaging based on risk communication strategies.  Message examples using odds ratios (“You are 5 times more likely to get in an accident during tomorrow’s commute than during a typical commute”) and normative strategies (“In a similar storm last month, an estimated 10,000 commuters shifted their commute time reducing their risk for accident and injury. Increase your odds of a safe commute be leaving early today.”) will be provided.  The potential effectiveness of these messages will be explored based on driver feedback.