U.Va. Study: Urban Sprawl Delays Ambulance Arrival in the U.S.

December 1, 2009 — Previous research has demonstrated links between urban sprawl and many of our most pressing public health issues, including obesity and traffic injuries. New research from the University of Virginia Health System shows that urban sprawl also causes delays in ambulances reaching their destinations in sprawling sections of large metropolitan areas in the United States. The study appears in the November edition of the American Journal of Preventive Medicine.

Hospital emergency departments all over the country are implementing partnerships with their local emergency medical services to improve pre-hospital care for patients. Such efforts may be stalled by delays in ambulances reaching their destinations.

"Emergency response time within communities is an important metric for demonstrating how well we are able to care for the needs of our citizens," said Dr. Matthew J. Trowbridge, lead investigator and assistant professor of emergency medicine at the U.Va. School of Medicine. "In the United States, development patterns have been mostly driven by economic efficiencies for developers and growth has gone largely unregulated. Unfortunately, we are only beginning to catch up with regard to understanding the health effects of sprawl as well as the cost and difficulty of providing necessary services such as reliable emergency care to people within these areas that we have created."

Trowbridge set out to prove that sprawling development increases the likelihood of delayed arrival times for emergency rescue vehicles. The research team obtained emergency medical service response times for more than 43,000 motor-vehicle crashes that took place within large metropolitan areas across the country. Sprawl at each crash location was measured using a county-level index that incorporates measures of residential density, proximity of residential and commercial areas, strength of town centers and street network connectivity. The relationship between sprawl and the probability of delayed ambulance arrival time – greater than eight minutes – was then measured while controlling for conditions than can also affect EMS response time, such as time of day, weather and presence of construction.

The analysis demonstrated that urban sprawl is associated with significantly increased EMS response time and a higher probability of delayed ambulance arrival.

"Some of our fastest-growing metropolitan areas are where the most sprawl has occurred. Exurban developments often follow what is termed a 'leap frog' pattern, meaning that they extend out in a line from city centers along major roadways. This means that EMS systems are being asked to cover larger and larger geographic areas with limited resources," Trowbridge said.

"EMS is one of those systems that force us to think about sprawl with regard to our cities these days because reliable emergency medical response is critical for everyone."

There is some favorable news; progress in redesigning communities with safety in mind is beginning to happen.

"Virginia has just passed legislation saying that new communities being developed are going to have to have a minimum requirement of street connectivity. This should allow us to have narrower streets and improve the livability of neighborhoods and it should help impact response times as well by creating multiple routes into neighborhoods for EMS providers," Trowbridge said.

As for the future, Trowbridge's next step is to examine emergency vehicle response times for other types of medical emergencies, such as cardiac and respiratory arrest, where even small delays of 15 to 30 seconds can be critical. For these types of emergencies, it will be important to begin examining the impact of neighborhood level features of sprawl, including its most prominent feature: the cul-de-sac.

"I see this research as a preliminary analysis. I think that subsequent analysis will benefit from being able to look at neighborhood-level effects, all the way down to a particular house in a particular style of subdivision," Trowbridge said. "I think that type of information system is coming and there are new tools becoming available that will allow us to start looking at those types of neighborhood-level effects. This would be very valuable information for consumers as they make home-buying decisions."

This story originally appeared on the U.Va. Health System Web site.