Drivers' Awareness of and Response to Two Significant Winter Storms Impacting Utah's Wasatch Front and the Correlation of Weather to Road Impacts During the Winter of 2012-13'

Over the past several decades, Utah has experienced rapid population growth, including a nearly 24% increase in the past decade. This has resulted in increased demand on Utah's existing interstate and arterial infrastructure. Recurring traffic congestion (i.e., peak commute times) and non-recurring congestion (i.e., weather-related) result in an estimated average annual cost of $250 million dollars in Utah. Recent Utah Department of Transportation (UDOT) studies have confirmed that inclement weather plays a significant role in non-recurring congestion and associated negative impacts with respect to delays, mobility, productivity, safety, and property damage. In an effort to measure, and potentially mitigate, weather-related traffic congestion, a cooperative research study between academic (The University of Utah), state (UDOT), federal (National Weather Service), and private sector (NorthWest Weathernet) entities is being undertaken.

As part of this project, driver awareness surveys were conducted for two significant winter storms along the Wasatch Front urban corridor. The approximately 400 responses for each event are used to 1) assess the weather information that drivers possessed prior to and during a storm; 2) determine sources of weather and road information; 3) explore uses, specifically modification of travel and/or commute plans, based on event information; and 4) examine perceptions of storm impacts and severity, including driver satisfaction with information provided. The first event was a band of heavy snow that impacted the evening commute on 10 January 2013. The second event, 24 January 2013, was the most significant freezing rain event to impact the Salt Lake City metropolitan area since at least the early 1980s. The data from the two surveys were aggregated into a single regression analysis. Participants typically used local TV and social media for gathering weather and road information, with other sources (UDOT and NWS websites and national sources) used less frequently. Use of Government sites (i.e., NWS and UDOT) and social information predicted changes in driver behavior, while broadcast media sources were not a good predictor, even though they were used by many respondents. Satisfaction with all information sources was high. The most frequent commuting changes reported were shifts in travel schedule, especially leaving early to avoid the storm, changing routes, and deciding not to travel. Self-reported actions from interviewees are compared to measured changes in speed, flow, and travel-time from the Performance Measurement System (PeMS) system utilized by the UDOT. The long-term goal is to use these results to provide insight on how the Weather Enterprise might more effectively communicate hazard information to the public in a manner which leads to improved response (i.e., change travel times, modes, etc.). With substantial behavioral change, it should be possible to improve safety and reduce the costs associated with weather-related congestion and associated delays.