Effects of Emergency Medical Services Times on Traffic Injury Severity: A Random Effects Ordered Probit Approach

Emergency medical services (EMS) play a vital role in the postcrash effort to reduce fatalities by providing first aid treatment and transportation to medical facilities. This study aims to analyze the time required for crash reporting and EMS arrival in fatal traffic crashes and to explore the effects of EMS time on the traffic injury severity. The time required for EMS reporting, arrival, and transport to hospital was calculated by location type and roadway functional classification using 2016 Fatality Analysis Reporting System (FARS) data. Subsequently, an ordered probit model was developed to identify factors contributing to injury severity considering EMS time. The average time for the crash–reporting duration is 5.38 min, the reporting–scene arrival interval is 10.52 min, and the scene–hospital interval is 34.72 min. The average crash reporting and reporting–scene arrival intervals were the longest on conventional roads in rural areas and the shortest on conventional roads in urban areas. The average scene–hospital interval was longest in conventional rural areas and the shortest on freeways/expressways in urban areas. The developed random effects ordered probit model shows that prolonged reporting–scene arrival and scene–hospital intervals result in more severe injuries. The result also presents that crash type, violation, age, location, lighting condition, and alcohol/drug involvement have significant effects on injury severity. The key findings from this study indicate that EMS times differ according to urban/rural location and road functional classification and that reporting–scene arrival and scene–hospital intervals have significant effects on injury severity along with various factors. It is expected that the findings from this study can be used to develop effective and practical strategic plans to minimize EMS reporting, arrival time, and transport to hospital and therefore decrease the traffic injury severity.


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  • Accession Number: 01686425
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 3 2018 3:00PM