Benefits of IdaShield Signs at Highway–Rail Crossings in Idaho: Crash Analysis and Usability Assessment Survey

This paper describes findings from a study that assessed the safety impacts of IdaShield signs installed at 1,341 highway–rail crossings in Idaho. IdaShield effectiveness was assessed with two measures: (a) a before-and-after analysis of crash data preceding and following installation of the IdaShield and (b) a usability assessment survey that measures users’ understanding of the IdaShield and changes in users’ responses because of the IdaShield. Before-and-after analysis of crash data revealed a significant 38.6% improvement in safety after IdaShield signs were installed. A separate analysis that used Wilcoxon signed rank tests found a significant 39.5% improvement in the daytime and 72.2% improvement at night, suggesting that IdaShield had an effect on improved safety during both daytime and nighttime conditions. The higher percentage of crash reduction for nighttime crashes indicated that some of the crash reduction of the IdaShield could be associated with improved sign reflectivity. In the usability ...