Identification of Secondary Crashes and Recommended Countermeasures

The objective of this study was to identify and analyze the occurrence of secondary crashes on roadways in Kentucky and recommend countermeasures to reduce their frequency and severity. Results show a small percentage of crashes coded as a “Secondary Collision” were confirmed to be a secondary crash based on the definition and requirement of “a crash occurring as a result of a previous crash”. It appeared that many of those miscoded as a “Secondary Collision” were the result of misinterpretation of what constituted a secondary crash versus a secondary event. Adoption of the definition used in this analysis, along with more training and data input quality control was recommended. A review of 9,330 crashes coded as a “Secondary Collision” confirmed 362 or 3.88 percent as secondary crashes, and matching collision reports for the previous crash were located for only 236 crashes. An alternative analysis involved a query of the CRASH database to determine the time and distance relationships between the primary and subsequent-related crashes. The algorithm was able to identify 87 percent of the secondary crashes that were previously identified with the extensive manual search and review of crash reports. Based on analysis of the severity associated with secondary collisions (362) identified in the 18-month period of 2009-2010, the overall costs were estimated to be $11,228,100 when considering “Economic Cost” and $33,636,100 when considering “Comprehensive Cost.