title: Driving exposure by driver age in Michigan.
abstract: BACKGROUND
  This study compared driving exposure between two high-crash-risk groups (16-17 and 18-24-year-olds), with a low-crash-risk group (35-64-year-olds). In addition, patterns of association between driving exposure measures and demographic and driving behavior variables were examined.
  
  
  METHODS
  Respondent's total miles, minutes, and trips driven were calculated within a 48-hour period, using state-wide survey data collected in 2004 and 2005.
  
  
  RESULTS
  The youngest drivers drove fewer miles and minutes, but a comparable number of trips as the two older groups. Employment and high vehicle access were associated with greater driving exposure for 16-17-year-olds and 18-24-year-olds. Employment, high household income, large household size, and low vehicle access were associated with greater driving exposure for 35-64-year-olds. More driving was done alone than with passengers present and during the day than at night across all ages. There was a positive association between two driving exposure measures (miles and minutes driven) and demographic and driving behavior variables, which did not extend to trips driven.
  
  
  CONCLUSIONS
  Driving exposure is directly related to stage of life. The entire sample of 16-17-year-old respondents were in high school, which directly influenced their driving times, destinations, and purpose. Those aged 18-24years displayed driving behavior patterns that were closer to the older drivers, while retaining some differences. The oldest drivers were likely to be shouldering the greatest household responsibilities, and their greater driving exposure may reflect this reality.
  
  
  CONCLUSIONS
  These findings provide new information about driving exposure for two high-risk and one low-risk group of drivers. They also raise concern over potential workplace safety issues related to teens' higher driving exposure, and concomitant crash risk, related to being employed. Future research should examine this issue more carefully so that evidence based recommendations can be made to enhance the safety of teens who are employed, especially those who are employed as drivers.
authors.affiliation: University of Michigan Transportation Research Institute, USA. jpehsani@umch.edu
authors.forename: J P
authors.initials: JP
authors.lastname: Ehsani
authors.forename: C R
authors.initials: CR
authors.lastname: Bingham
authors.forename: J T
authors.initials: JT
authors.lastname: Shope
mesh_terms: D000063:Accidents, Traffic; D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001334:Automobile Driving / Q000706:statistics & numerical data*; D003625:Data Collection; D004651:Employment; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007182:Income; D008297:Male; D008824:Michigan; D008875:Middle Aged; D055815:Young Adult