Road Weather Impact Based Decision Support Applications: Developing A Department Of Transportation Winter Severity Index

Adverse weather conditions are responsible for millions of vehicular crashes, thousands of vehicular deaths and billions of dollars in economic and congestion costs. Many transportation agencies utilize a performance or mobility metric to assess how well they are maintaining road access. This research focuses on the development of a winter severity index for the State of Nebraska (NEWINS). NEWINS is an event-driven index that was derived for the Nebraska Department of Transportation (NDOT) and its districts across the state. The NEWINS framework includes a categorical storm classification framework and climatological aspect to capture atmospheric conditions more accurately across diverse spatial regions. A ten-year (2006-2016) winter season database of meteorological variables for Nebraska was obtained from the National Centers for Environmental Information. Meteorological parameters were grouped into categories that subsequently provided a storm classification database. The NEWINS was based on a weighted linear combination to the collected database to measure severity statewide and across individual districts. The NEWINS results were compared to meteorological variables previously used in winter severity indices. This comparison verified the NEWINS differences observed in the ten-year period. To further validate the developed NEWINS, cluster analyses were performed on the weather variables and storm classifications. An assessment of the difference between days with observed snowfall versus days with accumulated snowfall revealed a 39% average reduction in days. The NEWINS results for the ten-year period highlight the greater number of events during the 2009-2010 winter season, and the lack of events during the 2011-2012 drought year. The NEWINS also shows strong differences among NDOT districts across the state with the general decrease in events from the western to eastern districts. Furthermore, storm classifications were compared to NDOT winter maintenance operations performance data for a sample winter season. Last, the 2016-17 winter season was computed to provide a testbed for the NEWINS procedure. It is expected that the NEWINS could help transportation personnel to efficiently allocate resources during adverse weather events, while balancing safety, mobility, and available budget. Further, the theoretical and practical contributions provided by the NEWINS can be used by other agencies to assess their weather sensitivity. Advisor: Mark R. Anderson