Online Program

Studying the Associations between Street Design Variables and Severity of Injury from Bicycle-Motor Vehicle Crashes

Tuesday, November 3, 2015 : 8:45 a.m. - 9:00 a.m.

Morteza Asgarzadeh, PhD, Department of Environmental Health, Harvard T.H.Chan School of Public Health, Framingham, MA
Santosh K. Verma, ScD, MPH, MBBS, Center for Injury Epidemiology, Liberty Mutual Research Institute for Safety, Hopkinton, MA
Rania Mekary, MS, PhD, Social and Administrative Sciences, Massachusetts College of Pharmacy and Health Sceinces, Boston, MA
Maryam Farvid, PhD, Department of Nutrition, Harvard T.H.Chan School of Public Health, Boston, MA
Theodore Courtney, MS, CSP, Center for Injury Epidemiology, Liberty Mutual Research Institute for Safety, Hopkinton, MA
David Christiani, MD, MPH, MS, Department of Environmental Health and Department of Epidemiology, Harvard T.H.Chan School of Public Health, Harvard University, Boston, MA
Background: Safety concerns are major barriers to cycling, preventing Americans from gaining the associated significant health benefits. Intersection design variables might contribute to the severity of crashes.  In this study, we examined the associations between environment design variables (i.e. intersection angle, street width) with bicycle-motor vehicle crash severity.

Methods: A total of 3350 crash cases were obtained from New York City (NYC).  The data included geospatial information about each crash location (i.e. latitude and longitude collected with a GPS device by the Police at crash site).  We used the Single Line Street Base Map, the geographic data from the NYC Department of Planning, and GIS techniques to extract information on street factors. Injury severity was classified as severe (incapacitating or killed) or moderate (non-incapacitating). The association between injury severity and environment design variables was examined using multivariate logistic regression analysis.

Results: As compared to orthogonal intersections, the odds of severe injuries were higher for crashes at non-orthogonal intersections (OR 1.40 95% CI 1.01, 1.96), and at non-intersection street segments (i.e. crashes that happened on streets outside intersection proximity) (OR 1.53 95% CI 1.12, 2.08). Road system and street width were not significantly associated with injury severity.

Conclusion: Bicycle-vehicle crashes at non-orthogonal intersections are more likely to result in higher injury severity.  These findings suggest that non-orthogonal intersections and non-intersection street segments may warrant priority for protective interventions such as bicycle signals at intersections or protected bike lanes (i.e. cycle tracks) in non-intersection segments.

Learning Areas:

Environmental health sciences
Occupational health and safety
Public health or related research

Learning Objectives:
Describe the association between street design variables and severity of injury from bicycle-motor vehicle crashes. Discuss the utility of GIS extracted variables in injury prevention research.

Keyword(s): Geographic Information Systems (GIS), Planning

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am the primary Author and lead investigator of this project. I am a Chief Research Fellow at Harvard School of Public Health and collaborate with Liberty Mutual Research Institute for Safety. My area of expertise is conducting injury epidemiological studies to understand ways that the design variables of the built environment can impact risk of various forms of injuries particularly bicycle-motor vehicle collisions.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.