Research Snapshot: Civil engineers identify factors influencing bicycle crash severity in urban areas, provide recommendations for safety improvements


The idea

Using historical crash data, data collection, advanced classification models and machine learning algorithms that encompass critical factors in bicycle crash outcomes, Vanderbilt engineers Ishita Dash, Mark Abkowitz and Craig Philip developed an analysis that will result in a set of policies and actions that transportation planners nationwide can use to mitigate cyclists’ safety risks.

The team reviewed bike crash data from Nashville and Memphis, Tennessee’s two largest urban areas, and identified the features that shape crashes that result in fatalities or debilitating injuries to cyclists. These factors, which have been identified in other research across the country, include:

  • inadequate lighting conditions
  • crashes on roadways (rather than at intersections)
  • higher speed limits
  • high daily motor vehicle traffic
  • greater number of lanes
  • weekend traffic

This prompted the study team to recommend initial improvements to road lighting conditions, protected intersections and dedicated bike lanes on roadways, speed management techniques and traffic calming measures. A particular area in need is the introduction of physical barriers to minimize direct contact between car drivers and cyclists on roadways. These recommendations will be further defined as research and analysis continue.

Why it matters

The research conducted at Vanderbilt will shape road safety across Tennessee and may be applicable nationwide.

Pedestrians, cyclists and people who use wheelchairs accounted for approximately 20 percent of the 42,915 people who were killed in motor vehicle crashes in the U.S. in 2021, an increase of 13 percent over 2020, according to the National Highway Safety Administration. “It is up to all of us to keep those who walk, bike or roll safe as they travel,” Transportation Secretary Pete Buttigieg said in a statement.

The risk mitigation strategies the researchers have identified form part of a safe system approach, where several layers of protection work together to prevent severe crash outcomes. States, counties and cities may be able to use federal funding to implement these protective measures.

Part of the once-in-a-generation investment of $350 billion in highway programs through the Bipartisan Infrastructure Law includes the National Roadway Safety Strategy. The NRSS is the U.S. Department of Transportation’s comprehensive approach to significantly reducing serious injuries and deaths on U.S. highways, roads and streets.

“Because of the Bipartisan Infrastructure Law, states have new resources to improve safety for vulnerable travelers, make our roads safer and more accessible for all, and help move us closer to reaching the ultimate vision of zero fatalities,” Buttigieg said.

What’s next

Dash, Abkowitz and Philip are conducting further studies to provide an explanatory analysis of pedestrian crash severity in urban areas and to identify specific safety interventions for pedestrian and bicyclist severe crash locations in Nashville. They also may recommend changes to the Code of the Metropolitan Government of Nashville and Davidson County. They are working with computer vision and empathic analytic technologies that capture behavioral indicators to collect non-motorized traffic count and cyclist perception of safety at various locations in Nashville to further pinpoint where safety enhancements are warranted.

“With advancements in information technology and data analytics and using a data-driven approach, we can better understand transportation risk and safety issues,” the researchers said. “This approach is also transferable to other road users to achieve optimal safety for all modes of transportation.”


This research was funded by a Congestion Mitigation and Air Quality grant administered by the U.S. Federal Highway Administration and awarded by the Tennessee Department of Transportation.

Go deeper

The article “Factors impacting bike crash severity in urban areas” was published in the Journal of Safety Research in August 2022.