Temporal dynamics of hazard duration modeling of emergency medical service in interstate crashes

This study investigates emergency medical service response dynamics in interstate crashes using hazard-based duration models. Analyzing 6,415 crashes on Louisiana (2019–2021), it examines three critical intervals: arrival, on-scene, and transport times. Fully parametric models with random parameters assess the influence of crash type, roadway geometry, environmental, and temporal factors. Beyond identifying average duration effects, the study shows that factors impacting EMS response did not operate uniformly across time. Rain was associated with shorter on-scene time in 2020, while open-country crashes showed shorter ambulance arrival times in 2021. Similarly, morning and midday crashes were associated with shorter transport times in 2019–2020 but longer in 2021. Crashes involving no driver protection system shifted from shorter EMS active and transport times in 2020 to longer in 2021. Findings suggest that EMS planning needs to adopt more adaptive strategies, including rural ambulance pre-positioning, time-of-day-based staffing, weather-responsive dispatching, and real-time routing support.