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Impact of population density on collision rates in a rapidly developing rural, exurban area of Los Angeles County
  1. Kelly Fischer1,
  2. Isabelle Sternfeld1,
  3. Douglas Sloan Melnick2
  1. 1Los Angeles County Department of Public Health, Injury & Violence Prevention Program, Los Angeles, California, USA
  2. 2Los Angeles County Department of Public Health, Service Planning Areas 1& 2, Area Health Office, North Hollywood, California, USA
  1. Correspondence to Isabelle Sternfeld, Los Angeles County Department of Public Health, Injury & Violence Prevention Program, 3530 Wilshire Blvd., 8th Floor, Los Angeles, CA 90010, USA; isternfeld{at}


Objectives To determine if the commonly acknowledged relationships between population density and traffic collisions are found at the subcounty level and to describe how collision characteristics may vary substantially at a local level, with a particular emphasis on exurban areas.

Design Los Angeles County collision data were obtained from the California Highway Patrol and the census tract and service planning area (SPA) for each collision were determined. The correlation between population density and collision rates by census tract was calculated within each SPA and for the entire county. Primary collision factors were compared for geographic areas of different population densities within one exurban SPA in Los Angeles County.

Results An inverse relationship was found between collision rates and population density within Los Angeles County. Primary collisions factors were different in areas of the county with different population densities, with driving or biking under the influence particularly common in the most rural area.

Conclusions Subcounty analyses are very important to the study of traffic collisions. Traffic problems in rapidly developing exurban areas may be quite different from those in older, more established areas.

  • Motor vehicle occupant rural mortality surveillance
  • mechanism
  • violence
  • fall
  • firearm
  • populations/contexts
  • ecological study
  • methodology
  • geographical/spatial analysis

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  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement This article is based on a secondary analysis of data. Additional unpublished data from this study are unavailable.