A new study from University of Iowa researchers examines how converting four-lane roads to three-lane roads impacts emergency responses. 

Faculty members Cara Hamann and Joseph Cavanaugh (College of Public Health) and Michelle Reyes (Driving Safety Research Institute/College of Engineering), biostatistics doctoral student Stephanie Jansson, and engineering alum Nicole Corcoran investigated these reductions in road lanes known as “road diets.” Prior research has concluded road diets are effective at curbing vehicle crashes, by providing a dedicated turning lane between two opposite flows of traffic. 

However, no research has been conducted to determine the influence of road diets on the time emergency responders take to arrive at incidents. Hamann and other researchers noted that many community residents nationwide were concerned road diets were prolonging emergency response time. 

To address this growing public concern, Hamann created and disseminated an open-ended survey to EMS and fire personnel in 10 Iowa communities that have road diets commonly traversed by emergency responders. Of the 163 surveyed first responders, more than half concluded there was either no difference (51%) or a positive difference (16%) in their emergency response time after the road diet implementation. The remaining 33% believed road diets were slowing their travel duration. 

For one of the Iowa communities, Cedar Rapids, Hamann also examined quantitative data on exact emergency response times, acquired from the Cedar Rapids Fire Department. Hamann discovered there was no significant difference in emergency response time after road diet construction.

Hamann believes these data, coupled with driver education, could erode public pushback on road diets. “We did not find any negative effects of 4-to-3 lane conversions on emergency response times, which suggests that any related negative public sentiments are not warranted,” Hamann says. “Our results also revealed drivers were often confused about where to pull over when encountering emergency responders on locations with road diets. Educating drivers can help resolve these issues and likely shift additional public and EMS perceptions toward the positive side.”

The UI research cohort all mentored first-author Corcoran throughout the research project. Corcoran is a 2021 graduate of the Industrial and Systems Engineering Master’s Program in the College of Engineering. The culminating study, “Impact of 4-to-3 lane conversions on emergency response,” was published online in Transportation Research Interdisciplinary Perspectives. 

The study was funded by the Iowa Department of Transportation.