Market basket analysis of safety at active highway-railroad grade crossings. (December 2019) - Saunders, William J.
Highlights: Results showed that signage had a positive but minimal effect on driver behavior. Unsafe driving was only reduced by 2.2% and safe driving increased by only 3.7%. Chi-squared tests confirmed that the results were statistically significant. The MBA effectively extrapolated on the comparative safety analysis. The MBA generated important associations and provided insight on driver behavior. Abstract: Introduction: Data from the Federal Railroad Administration show high numbers of incidents at the approximately 210, 446 highway-railroad grade crossings across the United States. One cause for this unsettling trend is the problem of drivers stopping within the dynamic envelope zone (DEZ) of the train while in queue. This research seeks to study DEZ stopping behavior at highway-railroad grade crossings by evaluating regulatory signage and further analyze variables that may affect this behavior. Method: A comparative safety analysis is undertaken to evaluate the effectiveness of the standard "Do Not Stop on Tracks" (R8-8) sign by using percentage change calculations and chi-squared tests. The study then conducts a market basket analysis (MBA) to extrapolate on these results and to identify underlying factors associated with observed driver behavior using variables influenced by visibility, perception, and maneuverability. Results: Rather low reductions in safety violations resulted from the R8-8 installation, including a 2.2% reduction in DEZ stopping behavior and only a slight 3.7% increase in compliance. The results of the MBA identified associations that affirmed assumptions about driver behavior, while other associations were not as direct but altogether helped broaden the understanding of interactions at grade crossings. Conclusions: This study concluded that the R8-8 had a positive but minimal effect on driver behavior at the grade crossings. The MBA successfully demonstrated its value by providing further insight on the safety analysis and by increasing the number of variables that can be analyzed simultaneously. The methodology offers the scientific community an innovative approach to analyzing driver behavior. Practical Applications: The results identified important variables for developing preventive measures, which will ultimately help reduce safety violations at grade crossings. The MBA can provide practical insight for railroad safety professionals and transportation engineers when determining problematic intersections and can be used to improve the education on grade crossing interactions.