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Member Research and Reports

Iowa Study Finds Police Cars are Nearly Twice as Likely to Crash While Responding to Emergencies

A new study from the University of Iowa shows the importance of drivers pulling over for police cars en route to emergencies.

The study from the University of Iowa College of Public Health finds that police cars are nearly twice as likely to be involved in a traffic accident when they’re in emergency mode than when they are not.

The study notes that police officers face myriad distractions while responding to emergencies. Driving at a high rate of speed while avoiding other vehicles, they have to respond quickly as the situation changes and often take sudden turns, sometimes off-road. They may be responding to a high-risk call involving violence while monitoring communications technology inside the car.

“These multitasks can divert the officer’s attention away from driving and significantly increase the risk of a crash, especially when those multiple tasks are executed while driving at a high rate of speed,” says Dr. Corinne Peek-Asa, professor of occupational and environmental health and study co-author. “If they must also evade cars driving in their path, driving becomes very complicated.”

The study looked at crashes involving emergency vehicles in Iowa between 2005 and 2013. The data showed that police cars were involved in 2,406 crashes during that time, 879 of which happened while in emergency mode, with lights flashing and sirens sounding. The researchers then used a model to estimate the total number of miles police cars drive and used those crash statistics to determine that cruisers are 1.8 times more likely to crash while in emergency mode than in non-emergency mode.

By contrast, the study found that ambulances and fire trucks were involved in only 528 crashes during the period, and the model indicated they were no more likely to crash in emergency mode than not. Dr. Peek-Asa says this is likely because ambulances and fire trucks are larger and more visible, and they don’t travel at such high rates of speed even while in emergency mode, due to their considerable size and lower maneuverability.

Bad weather and poor road conditions also contribute to police crashes in emergency mode, while weather did not affect ambulances or fire trucks. She says ambulances and fire trucks also are rarely on the road in non-emergency mode, reducing their overall exposure to a crash.

The researchers suggest that driving could be made much less taxing for emergency responders if other vehicles are proactive in moving to the side of the road when they see flashing lights and hear sirens. Several states have implemented these messages in their highway safety campaigns.

“As roadways in the United States integrate more features such as roundabouts and speed controls, and as our expectations for emergency response times become lower, safe driving by emergency vehicles will become an increasing challenge,” says Dr. Peek-Asa.

The paper, “Does crash risk increase when emergency vehicles are driving with lights and sirens?” was co-authored by Dr. Cara Hamann, associate professor of epidemiology, Ms. Tracy Young, research specialist in the College of Public Health, and College of Public Health graduate student Mr. Celestin Missikpode. It’s published in the April issue of the journal Accident Analysis & Prevention.