Emergency Response and the Built Environment: Does Urban Sprawl Delay Ambulance Arrival?

Objective: Minimizing emergency medical service (EMS) response time is an essential objective of prehospital care; yet the potential influence of the built environment on system performance is often not considered. In this study, we measured the association between urban sprawl and EMS response time to test the hypothesis that features of sprawling development increase the probability of delayed ambulance arrival.

Methods: EMS response times for 43,254 motor vehicle crashes were obtained from the 2000-2002 Fatal Analysis Reporting System; a national census of crashes involving ≥1 fatality. Sprawl at each crash location was measured using a continuous county-level index previously developed by Ewing et al. The association between sprawl and probability of a ‘delayed' EMS response (≥ 8 minutes) was then calculated using generalized linear mixed modeling to account for correlation among crashes from the same county.

Results: Urban sprawl is significantly associated with an increased probability of delayed EMS response (p = 0.03). This probability increases quadratically as the severity of sprawl increases while controlling for nighttime crash occurrence, road conditions, and presence of construction. For example, in sprawling counties (e.g. Fayette County, GA) the probability of a delayed EMS response for daytime crashes in dry conditions without construction was 69% (95% CI = 66%, 72%) compared with 31% (95% CI = 28%, 35%) in counties with smart-growth characteristics (e.g. Delaware County, PA).

Conclusions: Urban sprawl is significantly associated with increased EMS response time. This suggests that promotion of community design more consistent with smart-growth principles may improve EMS performance.