title: Driver hand-held cellular phone use: a four-year analysis.
abstract: BACKGROUND
  The use of hand-held cellular (mobile) phones while driving has stirred more debate, passion, and research than perhaps any other traffic safety issue in the past several years. There is ample research showing that the use of either hand-held or hands-free cellular phones can lead to unsafe driving patterns. Whether or not these performance deficits increase the risk of crash is difficult to establish, but recent studies are beginning to suggest that cellular phone use elevates crash risk.
  
  
  METHODS
  The purpose of this study was to assess changes in the rate of hand-held cellular phone use by motor-vehicle drivers on a statewide level in Michigan. This study presents the results of 13 statewide surveys of cellular phone use over a 4-year period. Hand-held cellular phone use data were collected through direct observation while vehicles were stopped at intersections and freeway exit ramps. Data were weighted to be representative of all drivers traveling during daylight hours in Michigan.
  
  
  RESULTS
  The study found that driver hand-held cellular phone use has more than doubled between 2001 and 2005, from 2.7% to 5.8%. This change represents an average increase of 0.78 percentage points per year. The 5.8% use rate observed in 2005 means that at any given daylight hour, around 36,550 drivers were conversing on cellular phones while driving on Michigan roadways. The trend line fitted to these data predicts that by the year 2010, driver hand-held cellular phone use will be around 8.6%, or 55,000 drivers at any given daylight hour.
  
  
  CONCLUSIONS
  These results make it clear that cellular phone use while driving will continue to be an important traffic safety issue, and highlight the importance of continued attempts to generate new ways of alleviating this potential hazard.
authors.affiliation: The University of Michigan, Transportation Research Institute, United States. eby@umich.edu
authors.forename: David W
authors.initials: DW
authors.lastname: Eby
authors.forename: Jonathon M
authors.initials: JM
authors.lastname: Vivoda
authors.forename: Renée M
authors.initials: RM
authors.lastname: St Louis
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D001288:Attention; D001334:Automobile Driving / Q000523:psychology / Q000706:statistics & numerical data*; D040421:Cell Phone / Q000706:statistics & numerical data*; D003625:Data Collection; D015438:Health Behavior; D006801:Humans; D008824:Michigan / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors; D012449:Safety