title: Bicyclist-bicyclist crashes--a medical and technical crash analysis.
abstract: BACKGROUND
  The purpose of this study was to analyze the actual injury situation of bicyclists focusing on accidents involving more than one bicyclist. A medical and technical analysis was performed as a basis for preventive measures.
  
  
  METHODS
  Technical and medical data were collected at the scene, shortly after the accident. Technical analysis included speed at crash, type of collision, impact angle, environment, lane used, and relative velocity. Medical analysis included injury patterns and severity (Abbreviated Injury Scale [AIS], Injury Severity Score [ISS]).
  
  
  RESULTS
  Five hundred seventy-eight injured bicyclists in 289 accidents from 1999 to 2008 were included into the study. Sixty-one percent were male (n = 350) and 39 percent were female (n = 228). Sixty-seven percent ranged between 18 and 64 years of age, 12 percent each between 13 and 17 years of age and older than 65 years, 8 percent between 6 and 12 years, and 1 percent between 2 and 5 years. Ninety-two percent of crashes took place in urban areas and 8 percent in rural areas. Ninety-seven percent of crashes occurred in dry conditions and 3 percent in wet conditions. Eighty-three percent of all accidents occurred during the daytime, 10 percent at night, and 7 percent at dawn. The helmet use rate was only 7.5 percent for all involved bicyclists. The mean Abbreviated Injury Scale (AIS) score was 1.31.
  
  
  CONCLUSIONS
  The prevalence of bicycle-to-bicycle crashes is high. Most of these accidents occur in urban areas. Bicyclists should be considered as minimally or unprotected road users, with an unsatisfactorily low rate of helmet use. Though the average level and patterns of injuries is moderate, most of the severe injuries involved the head and extremities. However, there was no significant correlation between frequent helmet use and sustained injuries to the head of major AIS.
authors.affiliation: Trauma Department, Hannover Medical School, Accident Research Unit, Hannover, Germany. stephan@mh-hannover.de
authors.forename: Stephan
authors.initials: S
authors.lastname: Brand
authors.forename: Dietmar
authors.initials: D
authors.lastname: Otte
authors.forename: Maximilian
authors.initials: M
authors.lastname: Petri
authors.forename: Christian
authors.initials: C
authors.lastname: Müller
authors.forename: Timo
authors.initials: T
authors.lastname: Stübig
authors.forename: Christian
authors.initials: C
authors.lastname: Krettek
authors.forename: Carl
authors.initials: C
authors.lastname: Haasper
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001642:Bicycling / Q000293:injuries*; D002648:Child; D002675:Child, Preschool; D004779:Environment Design / Q000706:statistics & numerical data; D005260:Female; D005858:Germany / Q000453:epidemiology; D006260:Head Protective Devices / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013997:Time Factors; D015599:Trauma Severity Indices; D014947:Wounds and Injuries / Q000453:epidemiology*; D055815:Young Adult