Quantifying Roadside Assessment for Highway Safety

Many of Kentucky’s two-lane rural roads pose an above average risk for fixed object crashes. In Kentucky, run-off-road (ROR) collisions with fixed objects account for 18.9% of all crashes and 41.6% of fatal crashes. Accordingly, ROR crashes are a significant public safety hazard that must be addressed through judicious investments in safety improvements. Until recently, transportation engineers and planners have mostly leveraged qualitative metrics to prioritize safety investments, however, qualitative methodologies are problematic because they may rely excessively on subjective opinion and intuition. This study applied methodologies and software from the U.S. Road Assessment Program (usRAP) to develop quantitative, objective roadside safety ratings for rural two-lane roads in the state of Kentucky on which 20 or more crashes occurred from 2010 to 2015. Kentucky Transportation Center researchers generated usRAP star rating scores following standard protocols and, to validate the methodology, compared those scores to the number of ROR collisions over the specified interval. Analysis revealed robust correlations between star rating scores (and star ratings) and crash data, justifying their as an objective measure of roadside safety. Researchers also delivered a comprehensive database containing over 126,000 records to the Kentucky Transportation Cabinet, which can be used to examine roadside severity and potentially inform future highway investments